Stripped differential stud
 

So an easy task of upgrading my diff bushings turned into a horrible night and I stripped my diff mount stud. How difficult is this to replace in the car or does it require dropping the subframe?

If you're repairing the subframe, you'd wanna drop it, cut it out, and weld in an appropriate bolt from the top (if my memory serves me right). There's not much you can do with the subframe in the car if you can't save the threads.

You tried to draw the diff up by tightening the bolt, didn't you?

Been there, done that. Got another subframe for $50. It's not as bad as you think to swap the the arms across.

I'm such an idiot, all I had to do was put the nut on without stripping it. It's got a pretty decent gouge in the stud about a quarter inch up, would it be worth trying to tap the threads or could the gouge weaken it? Car sees lots of abuse

Picture of gouge? I'd probably run it, if it's only one thread or so affected and you can get he thread cleaned up.

If this is the way I remember it, some of the stud is exposed when the nut is fully tightened. If the damaged area is below that spot, you could actually grind the damaged area away, or cut the stud shorter, and once the diff is bolted in, it would function exactly the same as before, except be a little lighter. A die run over the threads would be my first attempt at a fix if the threads are good for the first 1/4", since if you can get a few threads started fist, the die will probably clean it up fine.