[quote]I'll look into the shims for the springs. The car sat even (to my eye) on the original springs...but maybe the stiffer springs are exacerbating a tolerance issue? When my Barracuda had the 185/70-14s it the rearend looked fine, when I put the 255/50-17s the problem was obvious

Tires- Yeah, I've long noticed how poor the T/As are by modern standards but as we have talked about in this forum, there aren't really any superior options in the 15"/60 series range. What would you recommend.
_ 255/50-17s... they are the same dia as your rear tires though they are getting harder to find too...or something like this scroll down to the end of the post for pics. If you need/want to stick with 15s, there are the Cooper Cobras or the Mickey Thompson Sportsman S/R Tires or ET Street S/S Tires.