I just got the fuel pump kit for my 1968 merc 60 6hp. The kit had an extra gasket that was not on the original pump and it's not shown on the diagram. Is this kit for several different pumps that may require it, or do i just not know how to install it? I just installed the one gasket and the diaphragm, is this correct? It's how it was when i disassembled the pump.