I need a specific name for a part...

[vzSvx]

I need to replace 2 gaskets that were rotten and causing a leak between the two pipes coming from the engine and the converter. Somehow it got disturbed when my tranny was installed. They called it doughnut gaskets, but what is it really called so I can order it. The bolts also need to be replaced. The one large gasket going to the muffler is fairly new since my exhaust system was just replaced last year. Are there part numbers for these? I appreciate any info. Thanks.