I know the local O'Reilley has the right size gaskets for the Post-Cat flanges, but even then both of my joints leak anyway (coming from Cat pipes to muffler, muffler to tailpipe). Have a really sh...crappy cherry-bomb Exhaust and I'm guessing whenever that was installed the flanges got a bit warped. The gaskets help, but I may end up stacking 2 or 3 together and hope it makes a seal. I'm dreading the day i have to work on the more forward sections