i own a 01 b5 s4 6spd and its making a loud thumping noise from the rear and im not exactly sure if its the bearing or the rear differential.. when i drive up to 65mph to 80mph the noise gets louder and it doesnt matter if im on the gas or not the noise is still loud and i have looked under the car and the mounts and bushings seems to be fine but ive notice when i jacked up the rear with both wheels off the ground, the wheel have play i them(not wobbly) but i can turn it back and forth from front to back even with ebrake on. so im clueluess and in need of some help or some ideas on what it is.