What I would try if it were me is to cut the nut off the stud any way you can...cutoff tool with a small cut wheel, put a gouge in it and whack it larger inside with a big chisel...if you have a torch then heat the nut up good and then cut it in two with the cutting tip...something along those lines...I would not try to save the stud...I'll bet that the hole is enlarged anyway...
I would
not recommend trying to break the stud by tightening the nut to the point of stud yield....the hub is a decent grade of alloyed cast iron and the stud is high-tensile steel....you run the risk of warping/distorting the hub and will have to get another one...
As far as saving the hub once you get it apart...If I could not or don't want to find another one then I would find a machine shop and bore the wallowed-out hole oversize and drive in a sleeve that will be a friction fit to the hub and the new stud...or...just weld in another stud...but you are welding steel to cast iron...kindy tricky...brazing might be better....
Hopefully, though...maybe....
Hopefully it just spun the knurles off the stud and didn't enlarge the hole in the hub.
one can hope...I am just figuring and planning for the worst....
If it has spun I'm willing to bet that the teeth of the stud have worn down and may spin again, I'd plan on replacing it. They're cheap enough.
I tend to agree with
@Nero but I have not shopped for a replacement hub for mine, so I don't know...yet...
Unless you can heat treat it, you will warp the flange. Also drilling welds is difficult.
sage advice, here...
Cut the nut off (sawzall or cut wheel on a grinder), drive the old stud out and hope the hole in the axle/hub flange isn't fubared.
More sage advice...
Can you poke something skinny thru the brake adjuster hole and use it like a punch to seat the stud?
I never thought of that but I am going to stow this into my mental toolbox...this is a good idea...
Have you tried re-seating the lug with a stud installer ??? -- I know Lisle makes one
I like this idea too...more good ideas...
No hammers for the install, no axle removal.
Just thought of something...and it might be nutty...
How about jacking up that side so no oil runs out...undo the axle bolts and slide the whole assembly out and drill away the head of the stud from the back...?? then punch it forward...?