I have a 5.9L 2002 Dodge Ram. I am going to be replacing that Cat due to having a 160,000 miles on it and still stock. I am looking at

http://www.amazon.com/MagnaFlow-9910.../dp/B001HMB4DM

But my question is, where will my O2 sensor plug in? And how hard is it to cut the cat off, and weld it into place with the 2 into 1 style.

 

If you want to use a Magnaflow Cat I recommend this one (Magnaflow 94169) as it already has two O2 bungs.

 

I only have one O2 Spot to plug in, what should I do if I bought the one you suggested? How to block that off>

 

The cat comes with a plug. And you can buy additional plugs/bungs at a Auto supply house. I highly recommend using hi-temp anti-seize on all the exhaust related threaded fasteners especially SS. I have my front O2 sensor plugged into the "Y" pipe bung, wide band sensor plugged into the front bung of the cat and the rear O2 sensor in the rear Cat bung. I did not use anti-foulers and I have no codes being thrown.