Transfer Case Clunk in 2HI Only

WARNING: This page is about a different car, the 2007 GMC Yukon XL, 2007 GMC Yukon, 2007 Chevrolet Tahoe, 2007 Chevrolet Suburban, and 2007 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 2HI mode. Review the Symptoms - Transfer Case and perform the necessary inspections.
Incorrect fluid level or incorrect fluid	Inspect the transfer case for the correct fluid level. Refer to Transfer Case Fluid Replacement . Inspect the transfer case for the correct type of fluid. Flush the transfer case and fill with the correct fluid, if required. Refer to Transfer Case Fluid Replacement .
Excessive clearance between the slip yoke and the rear output shaft	Inspect for the following conditions: Worn slip yoke splines Worn rear output shaft splines Repair or replace the following components if faulty: Replace the slip yoke, if required. Refer to Rear Propeller Shaft Replacement . Replace the rear output shaft, if required. Refer to Transfer Case Disassemble and Transfer Case Assemble .
Excessive clearance between the slip yoke and the rear bushing	Inspect for the following conditions: Worn rear bushing Worn slip yoke bushing journal Repair or replace the following components if faulty: Replace the slip yoke, if required. Refer to Rear Propeller Shaft Replacement . Replace the rear bushing if it is worn. Refer to Transfer Case Output Shaft Seal Replacement - Rear .
Worn high speed teeth on the range sleeve	Inspect for the following conditions: Worn high speed teeth on the range sleeve Worn or missing input gear thrust washers Refer to Cleaning and Inspection . Repair or replace the following components if faulty: Replace the range collar if it is worn. Refer to Transfer Case Disassemble and Transfer Case Assemble . Replace the thrust washers as required. Refer to Transfer Case Disassemble and Transfer Case Assemble .
Rear output shaft bearing outer retaining ring	Inspect for the following conditions: Proper installation of the rear output shaft bearing retaining ring Excessive wear or damage to the retaining ring groove in the rear case half Repair or replace the following components if found faulty: Properly install a new rear output shaft bearing outer retaining ring. Replace the rear case half if the retaining ring groove is excessively worn. Refer to Transfer Case Disassemble and Transfer Case Assemble .