Exhaust manifold flange stud stripped. Options?

I just replaced both catalytic converters and muffler. Everything was bolt-on. One of the nuts on the exhaust manifold flange was extremely difficult to remove and I’m fairly certain it stripped the threads on its way off. I cannot get a nut to start on it, just spins and spins then falls off (The other two nuts went back on ok)- To make matters worse, the stud itself will take an external torx socket but that’s stripped too. What do you recommend for this? Can I cut new threads on, or is there some tool to get a good grip on it and remove/replace? Of course it’s the hardest one to get to, with the least amount of working room. Or should I just give up and take it to someone who knows what they’re doing?

Edit to add that I bought a few different styles of M8 x 1.25 nuts to try and none of them would thread on

 

It’s been a few years since I went through this same issue. I believe your best option is to get a new stud from Toyota, try and remove the stripped one with some vice grips . Plan B would be to force a smaller nut over the stud, perhaps cutting some new threads in the process.
If you’re gonna eventually have to pay a professional anyway, mind as well try everything you can first.
I think in this case, the old adage, “ A crossthreaded nut is better than two lock washers “ might hold true.

 

haha, reminds me of the Two Guys: "cross-thread is better than no thread"

 

I know which your nut/stud your talking about. I replaced my manifold + cats + mufflers a couple years back (took 2 long extensions). I believe your gonna have to take your cat back off so you can get access/movement to all three nuts/studs. Once off you can try the "Two nut trick" to remove the stud:

https://youtu.be/nFYEoWTX0YU?si=waAduW7wWoKLkuhq&t=1012

Studs can be bought at a dealer or online.

 

2 options. Option A is to remove the cat and try to use a tap or thread chaser to recut threads and hopefully, there's enough there left to hold together. Option B is to cut the stud flat and drill it out. I can almost promise after 22 years that stud will not come out. It will most likely snap before it comes off. Get some good drill bits PB blaster and go slow and it'll be ok.