hydrodriver

Our '99 has 175,000 on it. Right now on a hard bump I get a "clunk" on the left side in the back from hittin the bump -
Put 1/2 inch bolts in the upper shock holes last summer - there was a ton of play there and the existing bolts were a metric something or other, found the 1/2 inch to be about .020" larger in diameter, yet they still slipped thru the frame holes and the top of one shock. The other shock would not allow the bolt to go in. I tryed drilling the shock bushing but is was harder than the drillbit. My local jobber found me a piston pin out of a lawn mower engine just the right diameters - had to Dremel cut it to length but worked like a charm.
Still have this clunk on a bump - this AM with the rear wheels off the ground I can get about a bit over 1/16" on the left axle end play and duplicate the clunk - I do not get radial play so don't think it's the outer bearing. Any ideas before I pull axles and go looking? Thanks!