Dealer Service Information Bulletin 68-I-28 – 1967 & 1968 Pinion Gear and Washers, Pinion Pin and Needle Bearing Rollers Change
Bulletin 68-I-28 — Pontiac Motor Division Dealer Service Information Bulletin, Section 7E, dated November 17, 1967. Attention: Service Manager.
Subject: 1967 & 1968 Pinion Gear and Washers, Pinion Pin and Needle Bearing Rollers Change.
Short answer: For 1967 and 1968 Turbo Hydra-Matic transmissions, measure the outer diameter of the pressed-out pinion pin near its end to determine which replacement pinion kit to use: standard (.3928–.3930″) or larger (.4340–.4342″).
The inside diameter of the pinion gears and washers and the outer diameter of the pinion pins and needle bearing rollers are larger for 1968 Turbo Hydra-Matic transmissions, except for an initial number of transmissions built at the beginning of 1968 production.
Prior to this change, a production trial run of approximately 5,000 1967 transmissions were built with these larger pinion parts in the reaction and/or output carriers.
In addition, a limited initial production run of some 62,000 1968 transmissions were built with standard size (smaller) 1967 pinion parts.
Therefore, if service replacement is required for the pinion gears of a 1967 or 1968 Turbo Hydra-Matic transmission, it is necessary to press out one pinion pin and measure its outer diameter for size:
- If the size is .3928–.3930″, use replacement Pinion Kit, Grp. No. 4.175, Part No. 8623951.
- If the size is .4340–.4342″, use replacement Pinion Kit, Grp. No. 4.175, Part No. 8625913.
Note: When measuring the outer diameter of the pinion pin, measure near its end.
Carrier assemblies with larger pins (.4340–.4342″) are interchangeable with carrier assemblies with smaller pins (.3928–.3930″).
Content last modified: June 13, 2026 at 10:06 am
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