8.75 or Ford 9”???

Agree. I think ford used the locker cause there isnt a lot of room in the case for a decent posi, due to the third pinion bearing. Ive got a detroit locker in my 8 3/4, but it sure aint factory! Lots of factory nine lockers in boss and cobra jet cars, (though the cj ranchero i had, had a 3.25 open!)

You could well be right. That's a good point. I think they are really close in strength. But still the 9 inch is cheaper to build......unless you find a good dude like Roy that will sell them fair. I was real fortunate with the 9 inch I have. One of my customers at work just walked up and said "Hey Rusty, you want a Ford 9 inch for free? Come get" so I did. LOL