Catalytic Converter

I have a bad catalytic converter in my 1999 Jimmy. It is rattling and the check engine soon light came on for catalytic threshold. First, I have 84000 miles. Am I correct that the warranty is up after 80000? Secondly, is swapping one pretty easy? I looked and they have direct swap ones at the local auto store. They look pretty easy to swap, but please let me know if there are any issues to watch out for. Thanks for your help

It is a simple process, take out the old one and put the new one in its place, but unless you own a welder and can weld, your only option is to take it to a muffler shop. Might be me guys, but I wouldn't wan't to use clamps on your cat.

Hope this helps somewhat.