I have four dodge trucks. My 1997 RAM 4x4 with a 360 and auto transmission plugged the factory cat at around 175,000 miles. Cut it off with a sawzall, chipped out all the guts and welded it back on. Did the black tape over the check engine light and otherwise so no changes in perceived power or fuel mileage. Truck now has 315,000 miles and is still running fine.
Did the same with my 1993 Dakota 4x4 with v-6 at around 160,000 miles. It now has 265,000 miles and has not even thrown the check engine light. Fuel mileage went up one mpg and power seemed better than ever but no dyno proof just perceived and that could be because it had lost lists of power due to lack of proper airflow before I gutted the converter.
My 1992 2wd drive Dakota stopped up its converter just over a year ago and gutted its converter and welded it back. This Dakota is a V-6 with auto transmission and has acted up ever since. Can get it to run perfect at highway speeds but it will sputter at low speeds. Can twist screws and get it run great at low speeds but it will then backfire at highway speeds. Been frustrating. Have hit a happy medium where it runs o.k. at all speeds but not great like the other two. Anyone have a tip for the little 92 dakota? Putting a new cat on it would cost more than the book value of the truck.