Inspect for the proper gear oil levels prior to performing system diagnosis. Refer to Lubricant Change .

Low gear oil levels

Faulty oil seal or other type external leaks may contribute to lower than required fluid levels. Refer to Rear Differential Carrier Leak Diagnosis .

Fill to proper level with gear oil GM P/N 12378514.

Worn, loose, or missing differential mounts

Repair or replace the differential mounts as required.

Worn propeller shaft constant velocity joints

Replace the propeller shaft assembly. Refer to Propeller Shaft Replacement in Propeller Shaft.

Worn bearing in the torque tube assembly

Replace the torque tube assembly.

Bearing noise within the differential assembly

A "grinding" or "roar" type noise will increase or decrease relative to the vehicle speed.

1. Check for the proper fluid level. Fill as required.
2. If the noise continues, replace unit as required.

Gear set "whine" noise within the differential assembly

A "whine" type noise will increase or decrease relative to the vehicle speed (approximately 50-60 mph).

1. Check for the proper fluid level. Fill as required.
2. Replace unit as required.