Some Rivieras may experience a final drive noise and/or loss of drive due to an overheated final drive pinion bearing. A preliminary sign of this condition could be a loss of upshifts due to a worn governor gear in the transmission (appearing to be "apple cored," refer to illustration). Therefore, the final drive pinion bearings should also be replaced at this time.
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.