Hello all thinking about upgrading the 28 spline axles in our fox body mustang wondering about a 9" vs the 8.8"
I like the 9" but I don't hate the 8.8 rear either anyone replaced their 8.8 with a 9" with the same ratio and how much and what did you loose I'm assuming some MPH?
If I start from scratch there about the same cost, I believe the 8.8 has less drag but the 9 differential is stronger
just asking for input from those who have ran both, before deciding which way to go.
Thanks in advance for any help.

I like the 8.8 and it will be cheaper. We've been low 4.60s on 28s with an 8.8. The 9" will have higher ears so it will change the IC unless you put in a Lyons or Double AA upper relocation deal. Only back to back test ive seen was a super stock fairlane. 8.8 was about 5 hun faster. Vs aluminum center 9"

There have been a couple complete rears for sale on some of the Facebook marketplace sites in the last week or so, both 8.8's and 9's.
I've worked on cars that had both but can't say there is one better than the other. I do know on an aftermarket 9" housing the ears for the upper arms ar a really tight fit on the bushings. I struggled to remove the rubber ones and struggled more to install the spherical ones.

I've got a new 8.8 that I built for my car that im not going to use now. 33 spline. Its setup for a mini tub deal though. 9" ends, Trick lower brackets, TRZ billet shock brackets, link bracing in the front. I have everything including the brakes and correct 12" Billet specialities wheels. I'd sell it for what I have in it with no labor.

Blind Mule brought up a good point.

Combine the two. Put 9" ends on 8.8 housing. Eliminates C-clip eliminator kits which almost all leak. Then you just use 9" axles in whatever length you need. Yes 9" is a little faster, and 8.8 is plenty strong for most of us. If you go with a 9", as mentioned, the upper brackets will be higher, which will shorten the IC a little-and that sometimes helps, other times hurts. The factory triangulated 4 link isn't great anyway, but better than leaf springs. There are PLENTY of things you can do with the quadrabind suspension to make it work pretty good.