Ok so I have a 2001 Mustang gt with 4.10 gears and a cold air intake. I bought the car used from a private seller out of town so I'm aware there could have been some weakness and wear from hard driving from previous owners not to mention the beating I give it on a daily basis. I'm a person that likes a little show off session here and there which most of the time plays out very well. Saturday night I had stopped at a local spot to talk to some friends when another guy in a mustang started to rev his motor up at me. My natural instinct was to redline, dump the clutch, and smoke them through the lot. That succeeded but at the end of the lot I forgot about a small drainage ditch in the road. No bigger than your averaged sized pot hole. Now the car was sideways with the tires still spinning when i crossed over this "ditch". I heard a POP that resembled a tire blow out followed by some clunks that resembled a flat spot on a flat tire. I thought I blew one of the rear tires but upon inspection with a flashlight I found nothing wrong with the tires. I did drive it home which leads me to believe it's one of the shafts but I won't know until I tear it apart sometime this week. As the car rolls it feels like it snags on something, frees up for a full rotation then snags again. Haven't been under the car yet so I'm not %100 if it is in the rear end. Theres no whining or grinding noises or any noise or vibrations from the transmission. Does this sound like an axle problem? If so how do I determine if it's an 8.8 or 7.5 or if it even matters? Will 28 spline fit universally or do I need specifics? I'm in a rush to get the car going by this weekend as I have some other family coming down for a weekend cruise and I'm trying to get all the info I can so I can make it as quick as possible

All GTs came with an 8.8inch Rear end with an LSD differential and 28 spline axles. Unless the PO upgraded then that is what is your car.

Hard to tell what would/could be wrong without being there. If your axle did indeed break or snap, it may not JUST be the axle...you might need a new differential (probably screwed up the splines on the diff), you will definitely need new axle bearings on the side where the axle broke. It's time to jack the car up, look everything over (all suspension parts, bushings, etc) to ensure all is well, and then probably remove the diff cover to inspect the rear end.

Sounds like your in for quite the repair but no real way to tell unless you start looking at it.

Thank you for your reply. I'm going to get in on the lift tomorrow night hopefully. I'm really hoping it's just a shaft! ?

Turns out whoever did the gears did not tighten the ring gear bolts properly. Two came out completely while the rest where loose. One found its way inside and got itself lodged between the ring gear and the pumpkin. The snagging I felt was the stuck bolt catching the pinion gear. Luckily there was no major damage. No teeth were missing just minor abrasions and a lot of metallic shavings. I've ordered new ring gear bolts and will be reusing all internals.