I have a 2001 Audi A4 Quattro, 2.8L 30V V6 with the Tiptonic 5 speed automatic. It makes a clunking noise when you are making a slow-speed turn like in a parking lot. But it doesn't happen all the time. But it is becoming more frequent. It's almost reminds me or feels like the differential is trying to lock up as I pull into a parking spot. You can feel and here the clunking noise. But you really don't feel it in the steering wheel. Me and my friend put it on a lift and ran it at slow speeds, turning the steering wheel and stuff, and we cannot make it make that noise. And there is one other thing that it does. I don't know if it is related to The Clunking noise at slow speeds. But it has a slight... The best way to describe it is... A resonating vibration. That comes and goes. Usually seems like it happens when you're going downhill off the gas at around 50 to 55 miles per hour. The half shafts, ball joints, tie rod ends, upper control arms, lower control arms, they all seem to be working properly. I hope maybe one of you all can shine some light on this problem.