Rear end
 

what is the stock rear end on 99-04 mustangs?

The GT's have a 8.8" rearend 3.27 gear, with 28 spline axles, and limited slip differential.. The axles are pretty weak, and the differential isn't too strong either..

8.8's are a crap shoot. Some guys can go all season on a stock rear some have broke on the first pass. But they are generally pretty strong. Alot stronger than the GM 10 bolt. If your gonna put any type of sticky tire on it I'd build it up first. -Mark

im getting ready to throw some headers and pulleys on it, after that the cam and im thinking a 3000-3500 stall, should i put 4.10s or 3.73s what do you guys would be the best for what im going to do?

the stock rear end will take most anything an NA combo can throw at it imho. The axles being the weak point, welding the axle tubes is also adviseable, after 400whp, it may need work though. Stock Trac Lok is nice, very streetable, and cheap to rebuild.

A stock rearend might handle an auto N/A car all day long but not a 5 speed car.. They put too much stress on the rear under hard launches on sticky tires and will break the axles or spider gears in the differential.. The stock track lock is easy to rebuild and I have done it many times but who wants to rebuild a diff. all the time, it sucks.. I just went and bought an Eaton and haven't looked back since.. They are very strong and have been able to handle anything I though at it and thats alot..

I have 4.10's in my 5spd. I believe they would work out well for your auto as well.