RayN

The O2 sensor bolt broke flat to the pipe. Where can I get a used or new catalytic/mid-pipe for 99 RX300 AWD?

Lexmex

That piece comes as part of a longer system of piping. Not sure where you can get it used, but it isn't out of the realm of possibilities to make a new bung on to a similar piece of piping. I did something almost similar last year,

https://www.clublexus.com/forums/sho...d.php?t=245871

TunedRX300

Salim also has experience re-threading the bung. One can only sell new catalytic converter so it is almost impossible to find an used one.

Meetya

New Intermediate Pipe is $1000 ($1,240.07 MSRP) from a dealer.