NO REVERSE, FIRST GEAR ONLY STRIPPED INPUT DRUM SPLINES

Models Affected: Some 1984 and Prior Model THM 200-C, ;200-4R and 325-4L Transmissions

Some 1984 and prior model THM 220-C, 200-4R and 325-4L 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 occurence. The new hardened drum may be recognized by a black appearance from the heat treat process.

Any time a 1984 or earlier THM 200-C, 200-4R or 325-4L transmission is disassembled the input drum should be inspected to see if it is one with hardened splines. If not it is reccommended that a new drum part number 8648360 be installed.

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.