Stripped threads on the O2 port in a cat
 

So it's like the title says, the threads are all jacked up on the O2 sensor port (downstream) on my cat. I'm trying to think of the best way to fix this for the new sensor I'm installing. I've never had to deal with damaged threads on anything metal before, any ideas?

Here you go

The tool used to fix fouled (female) threads is called a tap. If you can figure out what the thread pitch of the port is, and find a corresponding tap, you may be able to repair the damaged port. Any major tool store will likely have the tap you need on hand.

Yep, that's the proper tool that you need. I stripped my threads as well for my Cat-converter, however, mine were just a few turns at the opening. I just used a dremel on mine to grind down the stripped threads and still able to install my O2 sensor.

I'm literally about to do this, I guess I should go the safe way and do all the pre-cleaning etc
Just destroyed my differential fill bolt :(

I stopped off at autozone during lunch and they gave me one for free! lol, gonna try this when I get home from work.

Wow, that thing fixed my issue in about 60 seconds lol