Peter Badore

The shop may not have reassembled your axle completely causing this problem. I had a 2000 2.8l 30V AHA engine in a manual transmssion Passat that required extreme pounding to remove the outer cv joint from the axle shaft and reassembly was essentially impossible. So I bought a new axle. When I looked carefully at the problem axle shaft end splines they were seriously deformed. Most A6 axles I work on can be disassembled and put back together without any problems but it sounds as if yours had tight fitting end splines. The tip off would be how hard was it to take drive off the outer cv joint during disassembly. A very good Audi dealership "tech" told me that sometimes he has to beat the "snot" out of them to get apart. So this issue is not unheard of.

Redneck Truck

Another update: They built another axle shaft using my inner, another outer, and a piece of tube. It's larger than stock but they say they've used that setup without incident before. Oh, and they put that axle together for the total cost of $0, so it's as good as the original shaft I gave them, only not defective. Installed it tonight, so far, so good. Will let you guys know if I run into any more issues.