Clunk in rear end

Hiya Guys,
I've got a 71 Rag with a 454 and 4 speed M22. I have a intermittent clunk that only seems to happen occasionally from a stand still. Don't have to hammer it and does not happen when cursing (even when snapped hard). Drive line feels solid. I've replaced all of the U-joints and bushings. It sounds like it's coming from the passenger side just behind the seat. Can't feel it through the shifter. Checked brakes and bearings seem to be ok. Could it be the trailing arm?? or?? Any help would be great.
Can be viewed at
http://www.cardomain.com/id/bigblock1971
Thanks

Did you read the thread "Differential noise" a few down. Not sure from your description if it is the same issue but I just went through the same thing by the sounds.

J,
I don't think it's the fluid. I had a 72 before and had the same problem that you mentioned especially coming off the highway the diff would bind!! I believe it has to be something in the else but thanks for the response!!