NOISE GROWL RUMBLE ON DRIVERS SIDE AT 32-63 MPH. GMC Truck Safari

SUBJECT: NOISE GROWL RUMBLE ON DRIVERS SIDE AT 32, 37, 51, AND 63 MPH (REPLACE PROPSHAFT)

MODELS: 1990 L VAN/L1O9 WITH STANDARD WHEEL BASE ----------------------------------------------------------------------------

THIS BULLETIN CANCELS AND REPLACES GMC TRUCK BULLETIN 9O-4A-74, PUBLISHED IN JUNE 1990 TO CHANGE THE PART NUMBER AND THE VIN BREAKPOINT ALL COPIES OF 9O-4A-74 SHOULD BE DISCARDED.

Some owners of 1990 All Wheel Drive "L" vans may comment about a noise that resembles "bad axle bearings," which occurs when driving under light or moderate load and peaks at 32, 37, 51, or 63 MPH. This condition will be improved by replacing the rear propshaft with a 3.5" propshaft (P/N 26026738). This new propshaft is more rigid and will significantly improve the noise/vibration associated with this condition.

VIN BREAKPOINTS:

Trucks made after the following VIN numbers are equipped with the 3.5" propshaft:

Chev LB133878 GMC LB510447

SERVICE PROCEDURE:

Refer to the M/L Service Manual (X-9030) section 4A, page 4A-5 for the procedure for replacement of the propshaft.

SERVICE PARTS INFORMATION:

Part Number Description Quantity ----------- ----------- -------- 26026738 3.5" propshaft 1

Parts are currently available from GMSPO.

WARRANTY INFORMATION:

For vehicles under warranty use:

Labor Operation: F1280

Labor Time: 0.3 hrs.

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.