I have a 1964 18hp Evinrude that runs perfect...except for the lower unit. I took it to a repair shop and was told that it would be better to try and find another lower unit due to that amount of damgage done to the old unit (by the previous owner). My question is does anybody know what year lower units will fit on mine? I heard that they didn't change the design much, so if I knew which years fit it would help me out in locating the lower unit. Thanks for any help you might be able to provide.