On my duster, since i was running a larger diameter tire, i made some shims and put them between the body and the front spring hangars. This centered the wheel in the wheel opening. Prior to this , the tire was pretty close to the leading edge of the wheel opening. I can't remember how much i moved the rearend back, seems like about 3/8. This might help with you driveshft issue, plus will give you more tire clearance at the front if you need it.