Changing rear ends but also driveshafts?

You think the driveshaft work will be pricey.....wait till you start gathering all of the rest of the parts for your 8 3/4 housing! The difference in length of the driveshaft between the 7 1/4 and the 8 3/4 is about 2 3/8". I'd look at where the seal is running on your yoke now and add or subtract as necessary to correct any current length problems. You need about 1- 1 1/4" of travel before the yoke bottoms out against the seal.