For 1990-2009 cars only
- Install the nylon inserts on the shift forks.
- Assemble the shift fork plates in the shift forks.
- Apply sealer GM P/N United States 12345493, GM P/N Canada 10953488, to the side of the new shift shaft expansion plug, if removed.
- Install a new shift shaft expansion plug into the transmission cover, if removed.
- Lubricate the shift shaft and the shaft bores with DEXRON® III or equivalent.
- Insert the shift shaft partially into the cover.
- Install the 1st/2nd speed shift fork. The 1st/2nd speed shift fork is the larger of the two forks.
- Install the selector arm and the C-shaped interlock plate. Push the shift shaft through the selector arm.
- The widest part of the interlock plate must face away from the cover.
- Install the 3rd/4th speed shift fork. The fork offset faces the rear of the cover and the 3rd/4th speed shift fork plate must be under the 1st/2nd speed shift fork plate.
- Push the shift shaft through the 3rd/4th speed shift fork and into the front bore in the cover.
- Rotate the shift shaft until the shift fork plate at the forward end of the shaft faces away from, but is parallel to the cover.
- Install a new roll pin into the selector arm and the shift shaft.
- Lubricate a new O-ring seal with DEXRON® III or equivalent.
- Install a new transmission cover to the extension housing O-ring seal.
Make sure the fork offset faces the rear of the cover.
Push the shift rail through the fork.
The selector arm roll pin hole must face downward and toward the rear of the cover.
Important: The roll pin must be flush with the selector arm surface. This will prevent the roll pin from contacting the shift fork plates during shifts.
