a body rear end ? 8 3/4 vs dana 60

the 8 3/4 is not a very efficient rear end due to the placement of the ring gear so low on the pinion gear...the dana 60 is much more efficient rear end...and the 9 inch furd is less efficient then the 8 3/4

swapped out a 8 3/4 for a strange dana 60....has not slowed the car down one bit..fact given the weather conditions I think the car is running faster with no other changes..