Hi all been having a tough time trying to get a straight answer from local part stores and shops on this issue.... Recently had to replace both front cats on the fiances libby due to previous owner ran with crap spark plugs and bad o2's and they plugged up. Ever since my brother and i replaced them i have been fighting leaks where the cat's hook up to the manifolds and the v band clamps are not making life any easier. I noticed the step down on the end of the manifold like it should have a donut gasket but there is not one on the manifold and after I thought about it it makes no sense for the converter end to be flared out and cupped then be band clamped to a flat manifold. No part store can tell me if there is supposed to be one there or not and honestly we never noticed if the old ones had one or not we changed them outside at night and it was 16 degrees and snowing but the old ones never leaked.. Been a battle with the leaks to pass emissions here in NY because one is causing issues with the downstream o2 and it's to loud. If anyone knows if i'm missing a donut or it's not meant to have one any info and help is much appreciated.