3 inch cat?

My cat just crapped and it stinks........

anyway my cat is rattling and my mileage is getting progressively worse. Does anyone know of a three inch catalytic converter that is tapped for the stock oxygen sensor? if not how about a compatible after cat oxygen sensor?

should I just get a generic 3" cat and weld up a nipple that fits the stock oxygen sensor downstream of it?

I tried searching but "3" is too short and is excluded from the search..........

I bought a Magnaflow high-flow online for $50. The exhaust shop welded a bung in and put the stock O2 sensor in for $20. Mine is just 2 1/4 but they sold 3" as well. I'll look for the website, I cant remember where I got it.