If you want to get into more detail, the Dana 60 is one of the more efficient rear ends, even more than an 8 3/4", while the Ford is one of the worst. It's a small percentage, but it is there.

It has to do with how close the pinion is to the ring gear centerline. Plus, the Ford has an extra bearing - more drag.

If you know the gear you'll be staying with, go Dana 60.