For 1990-2009 cars

Cause | Correction
--- | ---
DEFINITION: Inspect for proper gear oil levels prior to performing system diagnosis.
Low gear oil levels | Faulty oil seal or other types of leaks may contribute to lower than required fluid levels. Fill to the proper level with gear oil, GM P/N 9986115.
Worn propeller shaft constant velocity or universal joints | If constant velocity joint is damaged, replace the propeller shaft.
Bearing noise within clutch coupling assembly | This type of noise will decrease or increase relative to the vehicle speed.

1. Check for the proper fluid level.
2. Repair or replace the unit as required.

Gear set whine noise with RDM caused by incorrect backlash | This type of noise will decrease or increase relative to the vehicle speed.

1. Check for the proper fluid level.
2. Repair or replace the unit as required.