jaimesonlee

Guys, sorry if I missed anything, didn't read all the replies since I last posted. That's good you replace all those components but none of those are causing the problem. The problem is you need a rebuilt driveshaft (purchase here > http://www.jcwhitney.com/powertrain-...d=d74y2001g2j1) or you can disassemble and rebuild it yourself which can a decent little project in itself. Here's a video to help; it's not an A4 but the driveshaft is very similar as far as I know and it'll give you a good idea of what's required.
If you perform these repairs and the problem still persists then you have rear differential problems but I highly doubt that's the case. I have yet to do this myself as I have been clunking ever since I've owned the damn car. Hopefully I'll get motivated and do it as it would be nice to stop corking around. Hope this helps!

Eric V

I have a 2000 audi a4 2.8 quattro have a real bad thud in the rear starting to thing its the diff I'm wondering what other audis or passats can I snag a diff from from a junk yard that will fit what year make an modle

jaimesonlee

That’s interesting. I swapped a diff in mine before selling it and clunk was still there. Did all mounts (stiff mounts amplify the problem btw) and even bought a rebuilt driveshaft (which I was confident would remedy the clunk) and nothing. Unless the used diff I bought has the same issue (seller said never noticed anything) then I have no clue but I’m assuming the later was the issue. If you swap diffs, ensure you replace the axle flange seals.

To the person with the last post, I don’t think Passat will work bc only FWD I believe. Any B5 S4/A4/All road should work. GL!