S10/T10 P/U 2WD V6-262 4.3L (1988)
Drive Chain: All Technical Service Bulletins
Transfer Case - 231HD Noisy in 4WD High
Number:
91-63-7D
Section:
7D
Date:
August 1990
Corp. Bulletin No.: 067405
Subject:
NOISY TRANSFER CASE IN 4-HIGH
Model and Year:
1988-91 T TRUCKS WITH 231HD TRANSFER CASE
TO:
ALL CHEVROLET DEALERS
Some 1988-1991 T trucks may experience a noisy transfer case when the truck is in 4-high. The noise is caused by rotation of the chain and gears and is
transmitted through the transfer case shift linkage into the body interior.
A quieter "T" pattern transfer case chain and softer durometer shift rod grommets have been released to decrease the noise level. The chain can be
identified by two blue links while the previous design contained one blue link. The softer grommets are orange or beige while the previous design
grommets were white.
SERVICE MANUAL REFERENCE
Refer to the Unit Repair Section of the appropriate Service Manual for the proper replacement procedures.
SERVICE PARTS INFORMATION
Quantity
Part Number
Description
Required
15635937
Chain
1
15659238
Shift Rod Grommet
2
Parts are currently available through GMSPO.
WARRANTY INFORMATION
For vehicles repaired under warranty use:
Labor
Labor
Operation
Description
Time
T7036
Replace Chain and
2.1 hrs.
Install Grommets
FAILURE CODE: 92
