Transfer Case - Model 231 Noisy In 4WD High
90chevy25GMC NUMBER: 91-7D-13
GROUP: 7D TRANSFER CASE
DATE: SEPTEMBER, 1990
CORPORATE
NUMBER: 067405
SUBJECT: NOISY TRANSFER CASE IN 4-HIGH
MODELS: 1988-91 T TRUCKS EQUIPPED WITH NEW PROCESS MODEL 231 TRANSFER CASE
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 Grommet
Parts are currently available through GMSPO.