Beginning early in April, 1983 production the THM 325-4L transmission case was changed along with the coiled spring pin (refer to Figure 1) used to retain the pressure regulator valve bushing in the case. A larger solid steel pin (refer to Figure 2) is now used. This change was made to eliminate the possibility of case face distortion during assembly. Due to different sizes, these two pins cannot be used interchangeably. Furthermore, the new solid pin is a slip fit in the transmission case and may fall out if the transmission is rolled over; loss of this pin would enable the pressure regulator bushing to lose proper orientation, resulting in the loss of proper pressure regulator valve operation.
If replacement of either pin is required, use the following numbers to order the correct pin from GMWDD:
Figure 1 - Coiled Spring P/N 9437415 Figure 2 - Solid Pin P/N 141202
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.