I think I have a problem similar to Fikret. I have a wah wah wah sound coming from the right rear. It happens as the car starts moving and is directly related to the speed of the car. I tried rotating the tires and that didn't help. I checked the differential and it had oil. I jacked up the rear and put the car in gear and can hear the noise. Using a screw driver I listened at the differential end and at the wheel end of the drive shaft and the noise appears to coming from the wheel end. Could this be a bad bearing or could it be a bad CV (?) joint? How can you tell? How do you replace these items?