Popping clunk from back end when stopping... the saga continues...

[ORSOPERS]

Ok, I rode around in the trunk while my wife drove (not nearly as fun as it
sounds) and the upper strut mounts/bearings/bushings are not the culprit.  I
do have a tiny amount of play in the rear end, but I don't think that is it.
I did notice that when I removed the rear tires - I will be replacing the
very worn rotors - that if I put the lug bolts back in without the wheel on
there is a huge amount of play.  I can move the rotor almost 1/3 inch back
and forth and it makes a familiar clunk/pop sound.  Could this be it?  Could
the holes have worn bigger over the years/miles?  The rotors on the back are
original.  I would be very excited if that solved the problem.

Thanks again for all your help,

Rand Soper
'88 80q