NO REVERSE, FIRST GEAR ONLY STRIPPED INPUT DRUM SPLINES

1984 AND EARLIER THM 200-C AND 200-4R TRANSMISSION

Some 1984 and prior model THM 200-C, and 200-4R transmissions may have stripped input drum splines resulting in a loss of reverse, second and third gear ranges (refer to illustration) . In mid 1984 production, the drum was hardened in the spline area to prevent the possibility of this occurrence. The hardened drum (part number 8648360) may be recognized by a black appearance from the heat treat process.

Anytime a THM 200-C or 200-4R is disassembled, it is recommended that the input drum be replaced with the new hardened input spline drum (part number 8648360).

Refer to the appropriate Service Information Manual for proper installation procedures.

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.