Drivetrain - Transfer Case Output Shaft/Oil Pump
File In Section: 04 - Driveline AxleBulletin No.: 03-04-21-004
Date: May, 2003
INFORMATION
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(R) Automatic Transmission
(RPO M74) or ZF 6-Speed Manual Transmission (RPO ML6)
1. 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 0-ring - P/N 12478088
^ Oil Pump Screen - P/N 12478085
^ Connector Tube - P/N 12478086
^ Speed Reluctor Wheel - P/N 12478089
2. Inspect the rear output shaft in order to verity 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.
3. 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 0-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
Parts are currently available from GMSPO