Transfer Case Clunk in 4LO

WARNING: This page is about a different car, the 2008 GMC Sierra, 2008 GMC Cab & Chassis Sierra, 2008 Chevrolet Silverado, and 2008 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.

Cause	Correction
DEFINITION: During acceleration or deceleration, a clunk is heard or felt in the transfer case while in the 4LO range only. Review the Symptoms - Transfer Case and perform the necessary inspections.
High/low planetary carrier assembly	Inspect for the following conditions: Excessively worn planetary gears The planetary gears loose in the planetary carrier The input shaft for missing thrust washers or excessive thrust end play in the carrier Excessively worn high/low clutch engagement teeth on the carrier Refer to High/Low Planetary Carrier Cleaning and Inspection . Replace the high/low planetary if any of the above conditions are found. Refer to Transfer Case Disassemble and Transfer Case Assemble .
High/low internal gear	Inspect the high/low internal gear to front case fit for any looseness. Replace the front case half if the high/low internal gear is loose. Refer to Transfer Case Disassemble and Transfer Case Assemble .
High/low clutch	Inspect the high/low clutch engagement teeth for excessive wear. Inspect the high/low clutch to rear output shaft splines for excessive wear. Replace the high/low clutch if faulty. Refer to Transfer Case Disassemble and Transfer Case Assemble .