I just helped a buddy do the 8.8 swap on a 70 Duster and we used the Dr. Diff 1/2" kit and he had 275 tires on wheels with 4.5" backspacing. The tires were too close for comfort so he used a set of 1/4" spacers and they have about 3/8" clearance. You need to measure your wheel BS to see if you'll need the 1/2" kit or not
