NO SERVICE FRONT AXLE ASSY. (REPLACE COMPLETE AXLE ASSY.)

SUBJECT: REPLACING FRONT AXLE PARTS MAY RESULT IN VIBRATION (REPLACE ENTIRE AXLE ASSEMBLY)

VEHICLES AFFECTED: 1990-1992 "L" VAN

Each front axle for 1990-1991 L Vans is balanced with the pinion flange assembly modified to act as a harmonic member which reduces audible driveline disturbance.

Replacing the ring and pinion gear set, pinion flange assembly, or the pinion bearings may disturb the balance integrity of the axle and result in vibration.

Do not replace either the ring and pinion gear set, pinion flange assembly, or the pinion bearings in a 1990-1991 L Van front axle. If replacement of one of these parts is necessary, replace the axle assembly using the system balanced service axle assemblies listed below.

Prior to replacement of axle assembly, it is essential that the position of the propeller shaft relative to all of the driveline components be observed and reference marked. When replacing pinion seal, pinion yoke must be referenced to pinion, to assure re-assembly in original position. All components must be reassembled in the same relationship to each other. Attach propeller shaft to replacement axle first, then to the transfer case, and road test. If vibration is noted, then reindex propeller shaft to transfer case and test drive again.

SERVICE PARTS INFORMATION:

Vehicle Axle Ratio Part Number Description -------------- ---------- ----------- --------------------- L Van 3.42 26022779 Service Axle Assembly L Van 3.73 26022781 Service Axle 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.