I would check with your local salvage yard for the exhaust pieces you need. There is an arcane law about selling used catalytic converters, but if you state you just need the sections with the oxygen sensor holes to replace tore up bungs, they will usually sell you the entire piece for about $50. A catalytic converter assembly off a newer model should work.

I stripped out one of my O2 bungs on my 01 Rodeo while replacing the sensor, I used a bung wrench, liquid wrench, took all the precautions, but it would not come out without galling. I had to pull the transmission cable to get the exhaust piece out and back in on the drivers side.