1998 audi a4 2.8L Quattro 100k miles Transmission or AWD? or Driveshaft or Axle?

[Mr C]

I just bought this car knowing it needed a new transmission. I took it to a transmission shop who told me they rebuilt the transmission.

When I drive the car in stop and go traffic I hear a loud clunking noise. I think its the transmission but they told me its the AWD system. It doesnt happen all the time. It only happens in stop and go traffic. Like if I am stopped and give it gas it will give me a loud clunking noise. I hear it from a few different places, front and rear. Im not sure what it is.

Any ideas what it could be? Do you think its transmission related? What part of the AWD system would it be? Is there a way to disable the AWD to test?

What else can it be? AWD? Driveshaft? Axle?