Need to replace my riser gaskets. It's on a 1986 mercruiser 350 with center mounted risers. Mine used a gasket then a steele shim then another gasket. The problem i'm running into is finding the correct gaskets. They list 2 types full flow or a gasket that has 2 small vent holes. The one gasket looked like it might use the vent hole design but it's hard to tell since the gaskets disenagrated when removing the riser. Does it really make a difference as to which gasket i install? By the way it's raw water cooled engine
