Whats the thread size of the 02 sensor??

I just put long tubes on my car and I couldn't get the one 02 sensor out of my old mid pipe so i have an empty hole in my new h pipe, I had a spare 02 sensor but the threads are so shot I couldn't get any nut on there to match it up. For now I have a rubber expansion plug in there ....so who knows how long that's going to last. I just want to plug it for now with a bolt or something. I have a Tweecer and it's running in open loop all the time for now anyways so I don't need the stock 02 sensor in right now, I have a wideband in the other side. Anybody know?? :SNSign:

Thanks, never even thought of the drain plug idea.
This is starting to piss me off if I run it with one 02 sensor the afr is all over the place, at least on the passenger side where my wideband is. and sometimes one bank's injector DC% is WAY different than the other side. (it's learning and changing it? and going crazy since it is only reading one 02 sensor?)
But if I unplug the 02 sensors it runs exactly to how it's tuned via my Tweecer and doesn't go rich/lean on it's own. I am running it in open loop so I don't know why it would be doing this.