1991 and 1992 model steel wheels require use of Metric wheel nuts. 1990 and prior model year steel wheels require the use of English wheel nuts.
If a 1990 and prior model year wheel is assembled to a 1991 or 1992 model, the Metric wheel nuts will not mate properly to the 1990 or prior model year wheel.
When specifying 1991-1992 steel wheels, use only steel wheels (P/N 9591652) with Metric wheel nuts (P/N 9590477) on 1991-1992 vehicles.
Parts are currently available from GMSPO.
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.