will a 9" center section fit in a 8 3/4" housing? if not what are the differences? the reason im asking is that i have a 9" rear with a bent housing and access to a free 8 3/4" axle. is it a waste of time to pick it up?

I was unaware of a ford 8 3/4", do you mean 8"?

i think he means a chrysler 8 3/4" to my knowledge no you can't

ford does have 8 and 3/4 ring gears. let me do some diging to see if I can find the link.

These two gears are the same ratio- 3.00, but one is only 8 3/ 4” diameter, the other a true 9”.When gear is installed in the case, a true 9" ring gear will have very little clearance between housing and large gear (most noticable at bottom), while an 8 3/4" setup will have almost enough room to put your finger tips into between gear and case (but don't due it- it can hurt).Don't feel slighted if you find you only have an 8 3/4" setup, they are plenty strong, Ford used them behind the HiPo 289 applications in many Mustangs and others.



as taken from this site NINE INCH INFO (http://www.kevinstang.com/Ninecase.htm)