i have a 89 formula w/ a 9 bolt how much power can they hold not launching it or beating on it i also dont know the ratio but its got a t-5 and it tops out at 140 so im sure someone will know the ratio hahaha thanks in advance

 

You probably have a 3.45 ratio rear end and it can hold up to at least 400 HP.

 

An '89 TPI with a 9-bolt, so I'm guessing you have a dual-cat exhaust too? That would make the rear end ratio 3.45, as bjankuski said.

 

Some can't even hold up to stock HP.

 

How do you come to that conclusion? That are way stronger than 10-bolts.

As for 3.45 ratio....I pulled a 3.27 out of a 89 350/Auto GTA.

 

2.77 or 3.27 came with 350/automatics, while 3.45's came in 305/5-speeds.

 

Does anyone know where to get the Axle bearing retainers for the 9 bolts? I am having a bitch of a time getting them. From what I understand is that when they are installed they stretch to ensure a tight fit therefore not to be re-installed as they are already worn. Is there a rebuild kit that contains them? I am certain that someone has to have these stupid things as you need to remove them to change your axle bearings.

 

Just reuse the originals..I have a few times and the seals don't leak.