For 1990-2009 cars

# CASTING AND BOLT CHANGE THM 125 CASE COVER

BEGINNING MID-OCTOBER, 1980, A NEW DESIGN CASE COVER WENT INTO PRODUCTION FOR SOME THM 125 TRANSMISSIONS. BOTH THE NEW DESIGN AND PAST DESIGN CASE COVERS ARE BEING USED IN CURRENT PRODUCTION. THE NEW DESIGN CASE COVER HAS A LARGER MANUAL VALVE PLUG BORE AND A SECTION OF THE CASTING HAS BEEN REMOVED AS SHOWN IN FIGURE 1. THE CHANGES MADE IN THE NEW DESIGN CASE COVER REQUIRE TWO NEW PARTS: 1.A LARGER MANUAL BORE PLUG. 2.A SIX LOBE SOCKET-HEAD SCREW. SEE FIGURE 2. SERVICE INFORMATION 1.FOR SERVICE OF THE CASE COVER, REGARDLESS OF DESIGN, ORDER SERVICE PACKAGE NUMBER 8631957. PACKAGES WILL INCLUDE ALL PARTS NECESSARY TO SERVICE THE CASE COVER. 2.THE PAST DESIGN CASE COVER USES MANUAL BORE PLUG PART NUMBER 8631165 AND BOLT PART NUMBER 11503562. 3.THE NEW DESIGN CASE COVER USES MANUAL BORE PLUG PART NUMBER 8637091 AND BOLT PART NUMBER 8637087. 4.THE NEW DESIGN SIX LOBE SOCKET-HEAD SCREW REQUIRES A #40 INTERNAL SIX LOBE SOCKET-HEAD BIT AND HOLDER.

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.