Beginning with 1984 production of the THM 125/125C transaxles, a new transaxle case went into production. The changes in the 1984 THM 125/125C transaxle case are as follows:
1. The manual shaft hole was made larger in diameter to accommodate a larger manual shaft.
2. The manual shaft seal bore was made deeper to accommodate a double lip seal.
3. The transmission case casting was changed to accommodate a neutral start switch.
4. The Low and Reverse snap ring groove was moved toward the case sprocket face to accommodate thicker low and reverse clutch plates.
General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.