99.5 b5 a4 FWD manual transmission.

I have a noise that drives me crazy because I haven't found it.
-It's a single clunk noise every time i left off the throttle and the drivetrain shifts. Much more noticeable at low speeds. It's driver induced damage as it started after i launched the car right over some potholes and it was quite rough on it as the wheels spun and then caught.

-It sounds like someone left a trans mount loose and it clunks every time the drivetrain shifts. From the driver's seat it sounds like it's coming from the passenger footwell or firewall area.
-All trans and engine mounts are good. Even replaced the trans mounts....still have the noise.
-All motor mounts, trans mounts, and subframe mounts are tight.
-APR snub mount is intact and adjusted right. (I've actually busted an APR snub mount on my car before......I'm quite hard on it).
-No visible crack on trans mount aluminum brackets.
-All control arms are nearly new, I still inspected all ball joints and bushings.
-I also don't think it's suspension because the only way it happens is with drivetrain shift. No noise over bumps, while braking, turning, etc. Just a well definied pop or knock when i left off the the throttle. No noise when I accelerate.
-I don't have a dual mass flywheel. Single mass only. I also don't feel any additional drivetrain slack.

I honestly think I might have broken a chassis weld somewhere. If so, I can fix it, I just don't know where to find it.
This is an odd one. I'm just really hoping someone out there has had to chase the same noise before. I really thought it was a trans mount, but it just isn't.
The downside of being a product engineer (for a different manufacturer than Audi) is that I don't have a lift anymore like I did when I was a technician. If i had a lift and a helper, I'm sure I could find it. But i don't, so if anybody has run into this before I would really appreciate the assistance.

Thank you.

 

Have you solved it? Have the same problem on 98 1.8t FWD B5...