So I have took my Chevy K20 to the local speed shop to have some work done and one of the things I need done was a oil pan gasket. I was told by the shop that they were not sure if they could change the gasket because I have an after market pan on. I provide them with a new one piece gasket for my 454, which has a moroso pan on it. So i looked online to see if there are different types of pans for a chevy 454 and no there all pretty much the exact same, now maybe that is because the mounting surface is the same on the block, but i dont know thats why I am putting it out there. So correct me if I am wrong.