I want to reseal my lower unit - 1971 50 HP. My service manual shows a big rubber seal (kinda looks like a house on it's side) in the center of the unit. I came up with Sierra Pt# 18-2688 which covers 1971-1974, but it does not come with this rubber seal. The next seal kit on the list is Sierra 19-2659 which covers 1976-1988 and this kit includes the fat seal. When I clicked on the Mallory seal kit for 76-88, it has different seals/gaskets than the Sierra kit.
