Trying to get the 60 put back together before the weekend after having the head redone. I bought a few exhaust donuts for the manifold, just to have a spare or two incase they blow. They look small and I am not sure how they should seat. One is green and cloth on both sides, one is cloth on one side and metal on the other. They fit up into the manifold fine. I read somewhere else they are suppose to fit over the bottom pipe. Which it it and why are there more than one design?