Thanks everyone for the responses. Sounds like a helicoil is the way to go most likely. There's a T-coil too that I heard is a lot better.

Volvodad - Interesting that the shop fixing your brick was in Atascadero, I'm in San Luis actually.

The funny thing is that I drove over the grade both ways and parked twice before this happened.

I can see threads still present, and it did drive me home, even with a little bit of boost. I tried to tighten the spark plug more, and I'm not sure that I'm in the right threads. It almost feels like it's cross-threaded, or something is kludged up in the threads.

What are the odds that I had it cross-threaded before and now have the right threads? Or are the threads being visible not the same thing as them being good enough to hold a plug?

Thanks again,
Will
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1990 740 Turbo, on its way to stock specs, maybe beyond