seems like most newer (post acquisition) XJ's are 8.25's; some were dana 30's (similar ring gear size to a 7.25). they use a 1310 ujoint, so if you're shortening your stock driveshaft, you'll need a 1310/7260 conversion joint. they're a skoash over 2" wider than a stock A body 8.25/8.75 drum to drum. met a guy who had a stock '73 340 duster with an A body 8.25 in it, was the original owner. his rear wheels were custom magnum 500's, 15x7 with 3" backspace and 255/60R15's. that means with the XJ rear, stock mopar wheels (+.25" offset, so 4.25" backspace for a 15x7) should center the wheel almost perfectly.
