Noise in First or Reverse Gear

WARNING: This page does not describe the selected car, but rather 8 other vehicles, including the 2011 GMC Yukon XL, 2011 GMC Yukon, 2011 Chevrolet Tahoe, 2011 Chevrolet Suburban, and 2011 Chevrolet Avalanche. However, it is still accessible from the selected car via links, so may be relevant.

Checks	Causes
Center Support with 2-6 Low and Reverse Clutch Assembly (67)	Inspect for damaged or worn low and reverse clutch plates (463-465). Inspect for damaged low and reverse clutch backing plate (462). Inspect for worn splines on backing plate. Inspect for damaged low and reverse clutch backing plate retaining ring (461). Inspect for damaged low and reverse clutch piston assembly (470), spring (469), spring retaining ring (466), and center support assembly (459). Inspect for damaged low clutch sprag assembly (467). Holding the sprag assembly with the retaining ring facing up, and the inner race of the sprag assembly fixed, the outer race should freewheel counterclockwise. Inspect for cut, worn, or damaged low clutch sprag seal (468).
Output Carrier Assembly (68)	Inspect for damaged or stripped splines on the output carrier assembly.

Checks

Causes

Center Support with 2-6 Low and Reverse Clutch Assembly (67)

Inspect for damaged or worn low and reverse clutch plates (463-465).
Inspect for damaged low and reverse clutch backing plate (462). Inspect for worn splines on backing plate.
Inspect for damaged low and reverse clutch backing plate retaining ring (461).
Inspect for damaged low and reverse clutch piston assembly (470), spring (469), spring retaining ring (466), and center support assembly (459).
Inspect for damaged low clutch sprag assembly (467). Holding the sprag assembly with the retaining ring facing up, and the inner race of the sprag assembly fixed, the outer race should freewheel counterclockwise.
Inspect for cut, worn, or damaged low clutch sprag seal (468).

Output Carrier Assembly (68)

Inspect for damaged or stripped splines on the output carrier assembly.