With almost Grail-like mysticism, the “Delcotronic Transistor Controlled Magnetic Pulse Type Ignition System” is seldom, if ever, seen. Not  to be confused with the HEI of the mid 70’s, these were the first electronic ignitions available from Chevrolet. Known by such names as Magnetic Impulse, Mag-Pulse, Transistor Ignition or simply TI, these became the standard in heavy duty high performance Chevrolet ignition systems. This special transistor 
controlled ignition system was developed for high performance and racing use to replace the traditional point-fired ignition system that came standard on most vehicles. 

   With the development of capacitive discharge, multiple spark and multi-coil systems, these early milestones of Chevrolet racing history have almost been forgotten. From their introduction in 1963 in the Pontiac into the mid-1970’s, you’d be hard pressed to find a better ignition system for your race or high performance Chevrolet. These systems earned the praises of racers because they solved many of the problems inherent to the point ignition systems.

    Point triggered ignition systems can bounce (limiting rev capability) unless they have very high tension point sets. These high tension points are fine for short distance racing. However, when high tension points are used in an endurance racing event such as Trans Am or NASCAR, the rubbing block wears at a fast rate, resulting in increased dwell angle and retarded spark timing. The problem is critical in endurance events where the engine is expected to run at high RPM for an extended period of time. The TI system solved these problems and were reliable up to 10,000 RPM all day long. Racers quickly made these the “standard” in racing ignition systems for Chevrolet and Pontiac engines.  In their day, TI systems had widespread use in many racing series such as Trans Am, Can Am, road racing, NASCAR, drag racing and others. Many races and championships were won with TI systems.

   Delco-Remy first developed their new transistor controlled ignition system for the full-size Pontiac 389 and 421 engines on 1963 models. Throughout the 60’s, various other cars could be ordered with a TI system including Corvette, full and mid-size Chevrolets (including the 409), Chevelle, Chevy II and eventually as an “over-the-counter” (OTC) set up to install on any Chevrolet small or big block engine. The 1969 ZL1 was the only Camaro that came with a factory installed TI system.

  When the Camaro debuted in the fall of 1966, several racing series were underway and growing in popularity. To help bolster sales, Chevrolet wanted to prove their new car in competition- especially so in the SCCA’s Trans Am series. To do this they had to create a new obscure Camaro model that would be known as RPO Z28. By destroking the 327 engine with the 283’s engine had several high performance components that helped it to develop considerably more output than the advertised 290 HP. The first run of RPO Z28 Camaros occurred in late December 1966 for the fast-approaching Trans Am racing season starting with Daytona in early February. The majority of these were intended primarily for racers and delivered to select dealers to be set up as racing cars. The world would soon find out the Z28 was a serious contender at the race track. It would soon be a very popular vehicle on the dealership sales lots as well.

  Chevrolet wanted to be quickly competitive and put their “Engineering”, “Research & Development” and “Product Performance Liaison Group” to work developing racing components for the Camaro. At the time, official Chevrolet Corporate policy was that they were not involved in racing or sponsorship of any racing activity. However, behind the doors of these departments, they were very busy developing parts aimed at making the Camaro a successful racer. These parts were catalogued separately from the regular parts book as “Heavy Duty Parts”. They were available initially only to those that Chevrolet selected. Eventually these special parts became known and available to the racing public to satisfy SCCA and other sanctioning body rules. This incredible history is chronicled in Paul Van Valkenburgh’s classic book “Chevrolet = Racing?”- a highly recommended read. In their first year of competition
in 1967, the Z28 Camaros performed well in drag racing and only performed fair (at best) in their intended target- road racing. After correcting several problems with the suspension system, brakes, and engine reliability, Roger Penske and Mark Donohue’s Sunoco Camaros had incredible success in the Trans Am series in 1968 and 1969. 

    Many of the components that were developed for the Camaro racing programs were actually borrowed from other existing lines such as: Corvette disc brakes, Cross Ram intake manifold from the Mark IV engine program, and the cowl plenum induction from the 409. The Transistorized Ignition is yet another example of this. A new TI distributor,  #1111267, was made with an advance curve specifically tailored for the 302 engine. It was then a simple matter of borrowing the main harness from the full-size Chevrolet #2988218, along with  #6287841 starter extension harness, the existing ignition amplifier #1115005, the existing TI coil  #1115207, and making a special mounting plate for the amplifier #3916730. The ignition switch power feed extension #2987102 was borrowed from the 1966 Nova. These parts along with some miscellaneous items (wiring connector, ties, grommet, instruction sheets) comprised the first
Transistor Ignition systems for the new Camaro. It was only available as an over-the-counter (OTC) service part.

   Coincidentally, with the introduction of the Camaro in of this, several design changes took place that added a lot of confusion about these systems. The very limited production of these parts furthered the confusion. It is hoped that this article can clarify how the TI systems were used on the early Camaro. A convenient summary table is included to help the reader in understanding how they were set up. It is hoped this will aid anyone considering one of these systems for use on their Camaro. As this is a pioneer article on this topic, it is likely additional information will be discovered.

                                                 -Special magnetic pulse distributor
                                                 -Ignition pulse amplifier
                                                 -Mounting plate for amplifier
                                                 -Special TI Coil
                                                 -Wiring harness assemblies
                                                 -Miscellaneous parts (retainers, grommet, wiring connector, instruction sheets)

     All parts were available separately. For convenience, a kit was available that included all necessary items, less the distributor. This kit was called a  “Transistorized Ignition Unit”. These TIU’s helped prevent a lot of headaches when setting a system up. Most original systems were set up with a TIU. Today most are set up by pieces. The following sections will look at each of these TI components separately and discuss the changes that were made over the years.

   The initial offering for the TI distributor on Camaros was #1111267. Essentially it was a common TI distributor with an appropriate advance curve to suit the 302 CI engine. This has an iron housing with mechanical tach drive. It specified 14 degrees maximum mechanical advance at 2300 RPM (distributor degrees and RPM). It had a vacuum advance feature that most racers did not utilize. The “267” distributor remained available for all 302 applications from its initial availability in November of 1966. This was one of the distributors recommended in the Heavy Duty Parts listings and Chassis Preparation Sheets. This special publication was available when requested from Chevrolet for setting up a Camaro for Trans Am racing use. If you could write a convincing letter, Chevrolet Engineering would send these sheets out in a plain envelope. This special set of four photocopied pamphlets was referred to in Mark Donohue’s famous book “The Unfair Advantage”- another must read book. 

   An alternative distributor was listed that could be used as well. This is the highly prized “Ball Bearing” distributor #1111263. (Photo 1) This heavy duty version was initially released for the reverse-drive camshaft 427 big block racing engine. It has a special ball bearing on the upper part of the mainshaft instead of the usual bronze bushing. This distributor has an iron housing with a mechanical tach drive. This distributor also has a special reverse-drive distributor gear that permitted normal clockwise rotation of the distributor in this special 427 engine. It specified not have a vacuum advance feature. The plate inside the distributor was fixed in position. This distributor listed for $1,699.05 in the 1991 Chevrolet parts books! Another similar ball bearing distributor #1111095 was available without a tach drive, should you desire. 

  In order to use the “263” distributor in the small block 302 engine, it required some changes. First, the drive gear on the bottom needs to be replaced with the standard drive gear. Second, the lower oiling channel on the lowest boss should be grooved all the way around (360 degrees). This channel was only grooved about 270 degrees as it came from Chevrolet. If it is not fully grooved, like the standard small block distributor, it is possible to block the oil passage that feeds the right side camshaft lifter bank! If it is blocked, you will experience a quick failure of the lifters and valve train on the right side of your engine- NASTY PROBLEM! Third, you may need to revise the advance curve for your particular application. (Most racers would do this on any distributor)

  The “263” Ball Bearing distributor had an advantage when the Cross Ram dual 4-barrel set up became available for the 1968 Trans Am racing season. Because the “263” didn’t have a vacuum advance unit, it was easier to clear the #8 runner on the Cross Ram manifold. The distributor tach drive could be moved around to suit the application. The previously mentioned “267” distributor can be used but it is much more difficult to fit.

  Lastly, a third TI distributor is the one that came from the factory on the 1969 ZL1 cars (all 69 of them). These were the ONLY Delco-Remy Transistorized Ignition systems that were factory installed on the early Camaros. This distributor is #1111927. (Photo 2) This distributor has an iron housing with a mechanical tach drive.  It specified 14.5 degrees maximum mechanical advance at 2500 RPM. The distributor had a “dummy” vacuum advance without a hose attachment, that served to fix the advance plate into position in the distributor.

   It was entirely possible to use any of these three distributors on other Camaro applications. They were not necessarily limited to use on the 302 Z28 or 427 ZL1. It is even possible to use other TI distributors such as one from a Corvette, a Chevelle, or others. Additionally, parts were available to convert the standard aluminum distributor to a TI magnetic pick-up distributor. Chevrolet was just making TI setups available for use on Camaro race cars. 

  The amplifier originally specified for use in OTC systems is the #1115005. This amplifier has the “plug-in socket” style connector. (Photo 3) This amplifier had been experiencing some problems on other vehicles related to water leakage. Chevrolet and Delco were aware of this problem. Chevrolet had identified the moisture problem earlier in their “Service News” publication dated November 1966, just as the Camaro TI systems were coming out. To correct the problem, Chevrolet recommended drying the circuit board, then spraying it with lacquer or wire protective spray. They then recommended coating the cover gasket (old style gasket) with silicone grease. Additional grease should then be put between the cover and the base after reassembly. This had limited effect in solving the problem.

    Delco-Remy sent service bulletins out in April 1967 and another, revised bulletin in May 1968 with corrective measures. The problem according to them was 1) moisture leakage past the back cover seal into the main housing and 2) moisture intrusion into the electrical connection at the plug .

   To help correct the leakage problem, in January 1967, Delco-Remy designed a new cover plate and gasket. The original cover had a formed-in-place gasket while this new design cover had a separate rubber gasket. The first design cover is easily identified by its “curved edges” that cup around the amplifier housing somewhat. The new improved second design plate was flat. (The new cover #1960625 and gasket #1970226 could be bought at your local Chevrolet or Delco-Remy dealer.) 

   To correct the electrical connector leak, it was specified to have the connector harness plug be packed half full with a special Dow Corning silicone grease. Be aware that dielectric grease is a non-conductor of electricity and it can interfere with a good electrical connection.

   These continuing problems led Delco-Remy to a redesign of the amplifier, which they did in January 1968. Corvettes built after this date had the new #1115343 amplifiers (Photo 4) for their TI systems (RPO K66). This new Transistor Ignition amplifier replaced the earlier “005” unit. This new amplifier had a “pigtail” wiring harness approximately and gasket. By using the 27 inch pigtail harness, they were able to move the electrical connection away from the direct foul weather spray that plagued the first design amplifier. These two changes seemingly corrected the moisture contamination problems. (note: The May 1968 Delco-Remy service bulletin further specified “The assembly plant has been authorized to start packing the harness connector with silicone grease to effectively seal this area”. This would pertain to the new “343” amplifier. They were still concerned that even the new design could have troubles!)

   The second major problem with the TI amplifiers is their heat sensitivity. These amplifiers were built with germanium-type transistors. Germanium transistors are notably sensitive to heat. Some reports indicate were the best available at the time the TI systems were developed. Silicon transistors, a big improvement, were not yet developed. 

   Chevrolet specified mounting the amplifiers on the hood latch support brace where the amplifier would receive plenty of cooling air. This helped avoid heat related failure. It is important that the amplifier not become hot or any one of the three germanium transistors could fail. This heat problem has been addressed by modern technology with a replacement
circuit board assembly. Modern silicon transistor boards are available from M&H Electrical Fabricators, Inc. ph. (562) 926-9552 and several restoration parts suppliers. These are reported to be much more reliable than the originals. The author likes to use the original circuit board and has had no troubles-but he carries a spare wherever he goes!

  The circuit board inside the amplifiers on both #1115005 and #1115343 are the same. The only changes are the housing cover and the electrical connection. Many “343” amplifiers came with a special grounding clip that was attached with one of the back cover screws. (Photo 4A) The new “343”amplifier requires a different wiring harness-more about that later. The amplifiers have the appropriate identifying part number stamped on their housings. Many amplifiers had a date code stamped in ink on the back cover.

   One of the interesting things about the new “343” amplifier is that it was not listed in the “Heavy Duty Parts” lists until some time after May 1969. OTC TI systems apparently continued to come with the “005” amplifier despite the new “343” version being available. It is also interesting to note that ALL 69 ZL1’s which were built between late December 1968 and May 1969 came with “343” amplifiers exclusively. OTC systems had to wait for this upgrade!

   A special amplifier assembly became available when the new “343” amplifier came out. This kit (#3955511) included the new “343” amplifier and a special adapter harness connector to use with the old  “005” style harness. This kit was listed in the “Heavy Duty Parts” publications some time after May 1969. 

   Chevrolet specified that the amplifier was to be mounted on a special plate that was then attached to the hood latch support bracket. (Photo 5) This would place the amplifier directly behind the grille to allow cool air to flow over it. (Photo 6) The first plate was #3916730. This was used on the OTC systems 1967, 68 and some of 69. The May 1, 1969 Chevrolet Heavy Duty Parts list shows another number #3916739 for the 302, but this is speculated to be a possible typographical error. The same publication interestingly shows another plate #3954206 for 302, 396 and 427 applications. It is suspected this #206 replaced the earlier plate. The 1969 ZL1 used  plate #3954206 exclusively. After 1969, the plate was apparently dropped. On later applications (1970 and up), it was specified to mount the amplifier directly to the lower portion of the hood latch support brace.

   It is not known how these part numbers may have differed. This seems to be an area of confusion and might be a good topic for further research.

   TI systems use a special ignition coil. These coils have lower impedance than the standard ignition coils and are capable of flowing much higher current. This allows them to make a hotter spark at high RPM ranges when the spark plug voltage requirement is higher. If a standard coil is used, it will not be able to generate sufficient secondary voltage to work properly. Though there were several TI coil numbers, only two pertain to use on the Camaro. Part # 1115207 was the coil used for all OTC systems. (Photo 7)  Part #1115210 was the exclusive coil that came from the factory on the 1969 ZL1 Camaros. The only number available as a service coil was the #1115207. The “210” could not be purchased at the dealer. 

   The TI coil was unique in that the negative terminal was grounded directly either to the firewall or to the engine depending on the year and type of wiring harness. This differs from the standard ignition coil where the negative terminal is connected to the distributor wire and through the points to ground.

  As mentioned, these Transistor Ignition coils have a lower impedance across the primary terminals. Standard coils measure 1.24- 1.46 Ohms. The TI coil measures .41-.51 Ohms. The coils can be identified by a three-digit raised number on the side of the case. They are “207” or “210”.  These coils came with a special decal on the side indicating they were for the Transistor Ignition system. The first “207” coil was later replaced by a second version that had the full part # boldly stenciled in white on the side case (without any embossed numbers). A third later version made in Japan had a finely stenciled white part number and a different style coil wire tower on it, again without embossed numbers.

     This is where things get very complicated. Confusion results primarily because of the amplifier change. If you remember that each amplifier had a different wiring harness system, it will be much easier to follow. Definitions of “main” and “extension” harness complicated matters as well.  Keep these points in mind while reading through the next four subsections. Most of these harnesses are available in reproduction by M&H Electrical Fabricators ph. (562) 926-9552 or Factory Fit ph. (856) 933-0801.

            1967-69 OTC Wiring Harness-a borrowed system

      The first TI harness used on the Camaro for the 1967, 1968 and at least some of 1969 models was the “Ignition Pulse Amplifier Harness Assembly” #2988218 and  the “Ignition Pulse Amplifier Extension Harness Assembly” #6287841 (Photo 8). These two harnesses comprise the “main harness” as it would be known in later years. The “218” harness went from the amplifier, under the left fender, to the firewall. The “841” harness is sometimes called the “starter extension harness” as it goes down to the starter solenoid (as well as to the distributor and coil). Both of these harnesses have a separate ground wire wrapped into them. The “218” harness has a wire that grounds the amplifier to the radiator support. The “841” has a wire that grounds the coil negative terminal to the firewall.

   The third wire harness required on the 67-68 set up is the “Ignition Switch to Ignition Pulse Amplifier Wire Assembly” (WOW!) #2987102. (Photo 9) The 69 OTC system may have used this harness as well. (Note: Part # 8901973 or #6297792 cannot be used in this application.) This short harness went from the “218” harness through the firewall to the ignition switch directly. The hole to be drilled for this wire was specified to be 11/16 inch. 

  Detailed instructions were provided on Chevrolet instruction sheet #3916731 released November 4, 1966.These instruction sheets were a part of the Transistorized Ignition Unit #3921048.

          May 1, 1969 Changes to OTC Harnesses

    In the Chevrolet “ Heavy Duty Parts”  list dated to #6300109, which was listed for 302, 396 and 427 applications. Another “Ignition Impulse Amplifier Extension Harness Assembly” #2988219 was added for 396 and 427 applications. The #6287841 (starter extension harness) listed above remained available and was now listed exclusively for the #2986913 (ignition switch wire) was listed for the 396 and 427 applications. It is uncertain what ignition switch wire was specified for the 1969 302. It is likely that #2986913 was specified for all Camaro applications, replacing the earlier #2987102.

   These harness changes continued to use the #1115005 amplifier unit, despite that the new #1115343 amplifier had been released (more that one year earlier!) on the Corvette. TIU #3921048 continued to be available.

         The 1969 ZL1 Wiring Harness-getting simpler and better

   The 1969 ZL1 Camaros were built between late-December 1968 and May of 1969. There were a total of 69 built. They all had factory-installed Transistor Ignition systems.

   These cars used an “Ignition Pulse Amplifier Harness Assembly #6297791 (later revised in April 1969 to #6297688.) This harness was made to work with the new improved  #1115343 “pigtail” amplifier. This single “main” harness replaced the two piece main harnesses that were on the previous OTC systems. This new harness utilized the existing yellow wire from the starter solenoid making it unnecessary to have the starter extension harness previously used. 

   A special “Ignition Pulse Amplifier Feed Wire Assembly” #6297792 (Photo 9) was made to connect to the ignition switch connector at the base of the steering column. This provided the ignition switch power. The factory instruction manual specified a 3/4 inch hole be drilled for this wire. The ground wire for the amplifier was dropped. Apparently the factory was satisfied that the housing had an adequate ground by its mounting method. The coil had a separate short ground wire #6297793 (Photo 9) from the negative terminal to the coil bracket mounting bolt . Details of this installation can be found in the 1969 Assembly Manual under COPO 9560. 
 

          Post May 1969 OTC Wiring Harness Systems-the simplest to set up

   It is unclear when, but sometime after midyear 1969, the OTC TI systems adopted the simplicity and improvement of the ZL1’s setup. The change to the new main harness was made with the “Ignition Pulse Amplifier Harness Assembly” #6297688. (Photo 10)  The short coil ground wire #6297793 was also used.

   A new “Pulse Amplifier Ignition Feed Wire Assembly” #8901973 (Photo 9) was made that now connected to the fuse box wiring bulkhead connector in the engine compartment, after the coil positive wire was removed from it. This new generic wire allowed simple connection for all applications. It was no longer specified to drill a hole and connect to the ignition switch inside the car. The new amplifier #1115343 was used with this setup. The new amplifier will not connect to the previous “005” style harnesses. The instructions for setting this version up were in the “Chevrolet Special Equipment” manual (aka “Green Sheets”) revised 3-9-72, that are currently being reproduced. Instructions can also be found on Chevrolet instruction sheets #3965743 which were dated November 16, 1970. This was the last harness available for use on the Camaro OTC systems. Note that this version continued to be available for the 1970-72 Camaros.

   The few miscellaneous pieces deserve some attention. The These appear to be the same as the windshield washer hose “loop through” ties. Later versions, including the ZL1, specified the harness be taped in several locations. 

   The grommet was for either an 11/16” (early OTC)  or  3/4” (69 ZL1) hole drilled in the firewall to protect the ignition switch feed wire. 

   The electrical connector was to hook up the ignition feed wire to the ign. switch connector (early) OR to hook up the existing yellow starter solenoid wire to the main harness (later)

   A special wiring harness clip #3827371 (Photos 11, 11A) was made to hold the amplifier harness to the hood latch plate. This is similar, but not identical to, the trunk light wire harness clip. 

   Known instruction sheets in chronological order are: #3916731 dated 11-4-66, COPO 9560 ZL1 1969 Assembly Manual Instructions dated 12-16-68, #3965743 dated 11-16-70, and Chevrolet Special Equipment “Green Sheets” revised 3-9-72. It is possible others exist and the author would be interested in hearing from you if you have any. A copy of the appropriate instruction sheets is highly recommended before any attempt to install one of these systems.

   This was the kit that saved the installer from numerous headaches. It was a kit that included everything except the distributor. The content of these TIU’s changed over the years because of the many revisions previously described. It included the amplifier, ignition coil, wiring harnesses, mounting plate, grommet, electrical connectors, wiring straps and instruction sheets. In short it had all the rest of the correctly matched parts.

  #3921048 was the first such TIU. It was used from its introduction March 7, 1967 through at least 1969. The contents varied by the date at which it was purchased. The later Chevrolet “Green Sheets” list the “Transistorized Ignition Unit” #3997782 which included the parts needed to set up with the more weather resistant “343” amplifier.

   Some of the very first TI systems used two separate external resistors in the system. You may read about them in some early Transistor Ignition literature. Thankfully, all these resistances were built into all Camaro Transistor Ignition wiring harnesses. You need not concern yourself about them.

  Camaro TI distributors, like most others, came with a mechanical tachometer drive mechanism. It was speculated that the racer would use a mechanical tachometer. A mechanical tachometer can be set up but you may find it difficult to run the cable. The author has set one up successfully in a 1968 Camaro without butchering his vehicle, but it is challenging. You will find that your factory electronic tachometer will not read accurately if you try to drive it from the coil terminals (either + or - terminals) Apparently Stewart Warner used to make an adapter to drive their tachometers on a TI system. It is unknown if the adapter will drive a factory tach. 

  A special service bulletin from Delco-Remy for connecting a test tachometer to the system was released April 15, 1965. (#1.2D-19) To use a tune-up tach, first locate the two wire distributor connector. Find the side that the solid white wire is on. Connect your tachometer (+) lead to this point (easiest to attach on the other side of the distributors mating connector) The (-) tach lead should then be connected to the coil (+) terminal. (Yes- you read this right!) The author has successfully used a tune-up tach this way-but it seems to only work on tachs that have a separate power wire that attaches to the battery (+) terminal. Aftermarket performance tachometers (ones that don’t have a separate 12-volt power wire) seem to not function when attached this way. 

  Apparently, at least some of the 69 ZL1s came with a factory tachometer. It is unclear how they were set up and if they differed from the standard production tachometers. 

  We may be in luck however as Mr. Dave Fiedler is working on an electrical adapter to drive the factory tachometer. He is the owner of “T.I. Specialty.” His company services, repairs and supplies parts for TI systems. He is extremely knowledgeable about TI systems and the author highly recommends him. You can reach Dave at (765) 962-4265 and be sure to check his web site at www.tispecialty.com.

The author is indebted to the following people for their help and knowledge in refining this article into its current state. “No one is as smart as all of us”.  My special gratitude to:

                                                                Dave Fiedler of T.I. Specialty
                                                                Wayne D. Guinn, author of “Untold Secrets”
                                                             Larry Christensen of Camaros Plus
                                                                Bill Glowacki, Camaro Research Group
                                                                Rich Fields, Camaro Research Group
                                                                Jon Mello, Camaro Research Group
                                                                my wife Lori-for her understanding of my obsession
 
 

   Summarized in the following table are the components discussed in this article. This will help to discern these TI systems and their components. The next time you are at a car show, you may want to look carefully to see if you can identify one of these obscure systems. They are quite a conversation piece and an asset to the value of any car. Be prepared to look at a lot of cars until you spy one though!
 

	OTC  67- May 69	OTC May 69 Changes	69ZL1 Factory	OTC After May 69 (*1)
Distributor	1111267 (302)  1111263 (race)	1111267 (302) 1111263 (race)	1111927	1111267 (302) 1111263 (race)
Amplifier	1115005	1115005	1115343	1115343
Mounting Plate	3916730	3916739? (*2) 3954206 (all)	3954206	none
Coil	1115207	1115207	1115210	1115207
Main Harness	2988218 +6287841	6300109 +6287841 (302) or 2988219 (396,427)	6297791 (until 4/69) 6297688 (post 4/69)	6297688
Ign. switch wire	2987102 (67-68) (and 69?) (*3)	1969  (302)? (*3)  2986913  (396,427)	6297792	8901973
Ground wire	in harnesses	in harnesses	6297793	6297793
TI Unit	3921048	3921048	none	3997782
Instr. sheets	3916731	?	COPO 9560 in 69 Assy. manual	3965743 +”Green Sheets”

________________________________________________________________________________________
Notes:         *1-This change may have been in 1970. It was after the May 1969 Heavy Duty Parts list publication.

                   *2-This part number may be a typographical error in the parts book- likely was #3916730.

                   *3-Part number used is not clear for these applications. See text for recommendations.

Rev. August 11, 2002