How do you replace catalytic converter 91 town car?

Its easy, just buy direct replacement converters for both sides, make sure you get a right and a left. Direct fit converters are best as they are already welded and formed, I found mine on ebay. Then just follow the directions that come with them, just a few bolts hold them on. Make sure you replace the gaskets as well , mine came with the converters. Then sell your old converters for scrap platinum. Good luck.