In case anyone was wondering how it turned out:

Looks like the upper shock mount is a stud, with 3/4" nuts on each side. It bolts thru a hole in the frame, and the hole was wallowed out. Apparently it had been 'fixed' in the past by welding the outside nut in place ( instead of welding the hole back round ).

Well, I simply cannot access the inside nut because of the headders and engine mount. I wish I had thought to look at this while I had the engine out recently. Anyway.. for now I just welded the outside nut back in place. I put some serious weld on it, it shouldn't break loose again.

Should I have the engine out again in the future, I'll take the torch to it and fix it right.