8 3/4 vs 9" cost-wise

Pinion location in reference to the ring gear.

The 9" is at the best at robbing the most hp and putting the most pressure on the internals.
The factory 9" is even worse, but they have the best contact, and most drag, the aftermarket gear makers lose some of the drag by there gear design and do that thru the contact, but they only lose a little and the 9" is still the #1 power robber, the 9" has a ton of gear choices and pro gears making it easier to want to use.

The gm 12 bolt is the least at robbing hp, then the dana and 8.75.

The closer to center the pin is located to the ring the less power loss and pressure.