| Subject: | Design Change of Rear Output Shaft and Oil Pump Replacement Parts |
| Models: | 1999-2002 Chevrolet Silverado Pickup Models |
| 1999-2002 GMC
Sierra Pickup Models |
| All with Electronic Shift Two- Speed Transfer Case (RPO NP1) or Manual Shift
Two-Speed Transfer Case (RPO NP2) |
| EXCEPT Super Heavy Duty (SHD) with Allison® Automatic Transmission (RPO
M74) or ZF 6-Speed Manual Transmission (RPO ML6) |
- During reconditioning of the transfer case, if the rear output shaft is
faulty and requires replacement, the rear output shaft , old P/N 12473220,
is now being serviced with Rear Output Shaft Service Kit, P/N 88996610.
The service kit will include the following parts:
| • | Rear Output Shaft -- P/N 12384982 |
| • | Oil Pump -- P/N 12478084 |
| • | Oil Pump Suction Pipe -- P/N 12478087 |
| • | Oil Pump Suction Pipe O-ring -- P/N 12478088 |
| • | Oil Pump Screen -- P/N 12478085 |
| • | Connector Tube -- P/N 12478086 |
| • | Speed Reluctor Wheel -- P/N 12478089 |
- Inspect the rear output shaft in order to verify if the shaft is the replacement
design or the older design.
| • | On the replacement rear output shaft (1), the spline area for the oil
pump and the speed reluctor wheel is a larger diameter. |
| • | On the older design rear output shaft (2), the spline area for the oil
pump and the speed reluctor wheel is the same diameter as the rear bearing journal
diameter. |
- Install all of the components of the service kit, P/N 88996610,
if the vehicle has an older design rear output shaft. During assembly of the replacement
design rear output shaft, the O-ring seal for the oil pump and the retaining ring
for the speed reluctor wheel will not be installed.
The above information has been updated within SI. If you are using a paper version
of the Unit Repair Manual, please make a reference to this bulletin on the affected
pages.
Parts Information
Part Number
| Description
|
88996610
| Kit, Main Shaft
|
Parts are currently available from GMSPO.
