Just thought I'd dig this post up because I've started noticing something similar. I have a sneaking suspicion it may be a tail shaft bearing.
When I load up or back off I get a clunky kind of thump noise. Just one clunk, and only on load/unload.
Car is an MA61.
Ideas?
I had similar problems like your described. I had thought it was the lash on the diff but with the SA63 was the tailshaft uni joint failing. The MA61 had the clunks in and out of gear but once I got the LSD reinstalled and with the bearings replaced it has no clunk/noise no more... now it clunks into gear but most autos do that. My MA61 clunks into gear but not under load. I presume it's your lash on the diff that may need to be adjusted...
Anyone have any other ideas *to correct me as well *