popular swap is a toyota axle or a ford 8.8. lots of write ups on it.

 

Yeah Toyota 8" or Ford 8.8" depending on where you are and whats available, but basically anything from a light pick up or heavy sedan as long as you can get the ratios and centres you want, nothing is a straight fit, anything you choose will need to be shortened and have all the brackets added and wheel pcd and brakes fettled with.
The big bearing 28 spline axles on the 85' fb's are good for a gentle 400rwhp if you have an aftermarket center as long as you dont abuse it too hard with hard launches on big tyres.

 

thank you yeah i was thinking trying to find a wrecked fox body or something along that

 

i was just going to run small radials or maybe slicks on the street so it shouldnt be hitting too hard off the line but still you never know just a little too much psi off the line and its gone. Any idea where to get an aftermarket center though? that sounds like it might be a good way to go.

 

I had a Guru torsen in mine but no longer available, closest thing is Modena but still pretty big $$ especially with import from Aus. GSLSE equivalent (aus delivered s3) diff lasted quite well with 350 rwh and semi slicks, could never get grip in 1st or 2nd so no biggie. Was some axle twist evidenced after about 12 years of 350 horse and a year of about 440, about a 1/4 of a twist but still quiet , bearings still good and never failed. I believe Miata stuff fits but dont ask me what models,someone else will chime in, and even Kia Carnival. Have since gone Toyota diff just to be safe.

 

Are you planning on bigger rims and tires?