See if this is your issue:
File In Section: 10- Body
Bulletin No.: 76-16-12
Date: April, 1997
Subject:
Easy Entry Seat Noise, Movement, High Adjustment Effort (Replace Riser Assembly) Models:
1996-97 Chevrolet and GMC C/K Extended Cab and 2 door Utility Models Condition
Some owners may comment about the easy entry passenger seat making a rattle noise, rocking and/or being difficult to adjust.
Correction
Replace the Riser Assembly with P/N 12376289.
Service Procedure
Prior to installation, the new Riser Assembly must be painted to match the interior using the
paint system utilized at your dealership. Replace the Riser Assembly following the procedure in Section 10A2 of the appropriate year
C/K Service Manual.
Parts Information
P/N Description Qty Riser Assembly, 12376289 Passenger Seat 1