1984 300D rear end noise

[g.brew]

my 84 300d is making LOUD clunk-knock-thud noises from the rear driver side. It is consistant with wheel speed. It only does this about 50% of the time while driving(comes and goes) . From the sound of it, it seems like it should be something obvious to diagnose. I checked the CV boots for tears, ive wiggled the rear wheels to check for bearing play, checked muffler for any rattling, checked drive shaft for play, even took it to a reputable shop and after they charged me 130$ for rear sway bar links it still makes the same noises. F@#$!!!! Could this be a flex disc problem? Anyone have any ideas? Thanks!

Greg