EXHAUST NOISE 4.3L HO NEW EXHAUST ASSY. RELEASED

SUBJECT: EXHAUST NOISE (INSTALL NEW MUFFLER)

VEHICLES AFFECTED: 1990-91 M VANS WITH 4.3L ENGINE (LU2 "HIGH OUTPUT" VIN CODE B)

Some owners of 1990-91 M vans equipped with the 4.3L (LU2) Hi-Output engine may comment about a high level of exhaust noise during a variety of driving conditions.

If this condition is encountered, and there are no leaks found in the exhaust system, a newly released, quieter muffler/exhaust assembly (P/N 15650877) may be installed. This new assembly consists of a one piece exhaust pipe, muffler and tailpipe.

VEHICLES INVOLVED

Vehicles built after the following VIN breakpoint were manufactured with this quieter exhaust system.

1991 GMC 1GKDM19B4MB509183

SERVICE INFORMATION:

Part Number Description ---------- ---------------- 15650877 muffler assembly

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.