8.75 A body U joints?

Moving the axle back is a bad idea, since you'll need to modify the leaf springs, and the body. Mostly, its bad because the leaves are set up to counter wheel hop, with the axle mounted offcenter. This is supposed to cause the axle to use the leaf spring as a lever, and kills the harmonic that allows wheel hop. Long story short, moving the axle back will get rid of a lot of engineering.