from what i am told the ring gear/ pinion gear friction is less in the 8 3/4 than in the 8.8.
also the ford 9" is probably one of the worse rears made in pinion / ring gear friction. the biggest advantage and why so many people install it is the strength in both the gears and the large bearings in the axles and ease of changing gears like the 8 3/4.
availability of both parts and service techs to repair it and price of the parts is also a consideration of the ford 9".
I really really wish someone would test the 9" and give us an ACTUAL percentage loss against a few other rears. This "rumor" idea/statement about power loss has never been tested rear for rear, yet this idea just hangs around and around. The magazine that tested rears drove it via the engine and there is so much not scientific about that its hard to believe they actual took the time to do it.
