Transfer Case Clunk in 4LO

WARNING: This page is about a different car, the 2006 GMC Yukon XL, 2006 GMC Yukon, 2006 Chevrolet Tahoe, 2006 Chevrolet Suburban, and 2006 Chevrolet Avalanche. 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 pinion gears loose in the planetary carrier The input gear for missing thrust washers or excessive thrust end play in the carrier Excessively worn range collar engagement teeth on the carrier Refer to Cleaning and Inspection in Transfer Case - NVG 246-NP8 Unit Repair. Replace the high/low planetary if any of the above conditions are found. Refer to Transfer Case Disassemble and Transfer Case Assemble in Transfer Case - NVG 246-NP8 Unit Repair.
Annulus gear	Inspect the annulus gear to front case fit for any looseness. Refer to Cleaning and Inspection in Transfer Case - NVG 246-NP8 Unit Repair. Replace the front case half if the annulus gear is loose. Refer to Transfer Case Disassemble and Transfer Case Assemble in Transfer Case - NVG 246-NP8 Unit Repair.
Range sleeve	Inspect the range sleeve engagement teeth for excessive wear. Inspect the range sleeve to mainshaft splines for excessive wear. Replace the range sleeve if faulty. Refer to Transfer Case Disassemble and Transfer Case Assemble in Transfer Case - NVG 246-NP8 Unit Repair.