How durable are the factory rear ends in these cars? Could they stand a 350-ish horsepower motor or would they need replaced? Thanks.

 

Well that depends on a few things such as: tires, posi or open, what type of launch, and torque (not hp even though hp is a function of torque).

 

with street tires and a automatic , dont think you would hurt it but add traction or a stick shift and its only a matter of time , abuddy of mine has a 99 firehawk 6 speed with a stroker motor in it , he autocrosses it on his third set of gears now and he takes it wasy on the clutch domps and no strip use 460rwhp

 

I wouldn't plan on running it too hard, but whenever the wrong Mustang in the right place.....I was thinking about getting a 3.2x-3.4x posi and keeping the auto but getting 1200-1800 RMP stall converter. Factory tires, wheels, etc. Not real sure on the torue, but I would guess about 350 give or take 10-20 ft lbs.

 

You would probably be alright depending on what tires, but espically on the street where you have less traction you will be alright. I would recommend atleast a 2k stall though.

 

I have Cooper Cobras on now and they are less than 2 months old, so they will be there a while. Why a 2000 Stall? Durability, or just the take off factor? Would a posi-trac be better than the factory rear end? Thanks.

 

I have Cooper Cobras on now and they are less than 2 months old, so they will be there a while. Why a 2000 Stall? Durability, or just the take off factor? Would a posi-trac be better than the factory rear end? Thanks.

 

Acceleration only, especially with 350 ft/lbs.


Looking at your sig it says 91 RS L03, so if you rear is factory then probably odds are 1 in 100,000 or so that it has a posi. You would be much better with a Limited Slip of some brand.

 

Limited slip? What brand/gear ratio would you recommend? I was considering pos because of the transplant factor.

 

Gear ratio would all depend on the engine setup and where it made the most power. Limited slip, posi, same thing. I would recommend atleast a Auburn that came factory on third gens or early forth gens or a Torsen.

 

The rear end is a 7.something inch nine bolt right?

 

From your signiture on the on side you say you have a 91 RS L03 with 700r4 which would come with a 7.625 ten bolt rear.

 

Ok. Thanks for all your help. I now feel confident enough not to really mess things up. lol. I found a set of new Auburns for 330 or so.

 

Uh, one more question... how many spline would the rear axle be? Thanks.

 

Your 91, if factory, would have 28 spline axles.

 

Thanks. I thought that, but wanted to be sure for when I buy a rear end for the car.