3RD GEAR SHIFT LEVER VIBRATION RATTLE-NEW DESIGN SHIFT LEVER

1986-89 S,T TRUCKS

Some 1986-89 S/T Trucks may experience a shift lever vibration while the vehicle is in third gear. This condition may also be described as a rattle. The vibration may be most prominent on a coast down (deceleration) while in third gear.

Production Change

A new design shift lever was put into production during the 1989 model year. Vehicles which have the new design lever can be identified by the serial number on the transmission identification tag. An example of the tag and its location on the transmission is shown in Figure 1. Vehicles with transmission serial numbers equal to or higher than those given below have the new design lever.

Vehicle Serial Number Breakpoint -------- ------------------------- T Series 21564 S Series with 2.5L Engine 72267 S Series with 2.8L Engine 23911

Service Action

For vehicles exhibiting third gear vibration that were built prior to the production incorporation of the new lever, the shift lever should be replaced with the new design lever. Reference Section 7B-3 of Service Manual for replacement procedure.

The new design shift lever P/N is 15618925.

IMPORTANT: After shift lever replacement, assure that the boot assembly is positioned to ride as high as possible on the shift lever to reduce transmission noise into the cab.

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.