look at Jeep XJ cherokees, they have 8.25" rear ends, and are 59.5" wide drum to drum (about 2" wider than an A body 8.75). it should center the wheels about perfect in a duster/dart sport with factory offset rims, and should be able to fit at 255/60R15's, maybe all they way up to 275/60's. Auto's came with 3.55 gears, manuals 3.07's, and tow package 3.73's. just need a 1310/7260 conversion U joint if you use a stock 8.25" A body driveshaft.