Looking for help.

My L322 had a server vibration over the whole vehicle, after some investigation we found that this was the prop shaft, the centre bearing was deteriorated and it was out of position.

This was replaced and the vehicle vibration has now gone, but, I’m left with another issue: when accelerating hard from a standing start, there is a thudding / clicking noise and vibration coming from the rear of the vehicle. This only last for a second or so, and when the vehicle is in motion is stops. The garage dealing with this, have isolated the transfer box and tested the vehicle and the noise etc is still there meaning it is definitely coming from the rear of the vehicle. They also drained some of the oil from the rear diff to see if there was any metal visible and it was clean (that doesn’t mean there could be play in diff or even a tooth has snapped from the gear).

The garage are wondering if something is out of alignment, maybe this is what could have caused the original prop shaft to deteriorate, or if the rear drive shafts need replacing.

I’m looking for some advice before I start throwing money at it to fix the issue, has anyone else had this issue or similar symptoms?

Any advice would be massively appreciated.