I'm thinking about buying a 3.9 HP outboard from a local guy. The serial number is 2444631 and I was wondering that year that may be. One chart I found would suggest 1967, but another suggests 1968 or later. The guy selling it thought it was 1978, but I don't show them making this HP that late. It appears to be in good shape, so I was wondering what it is worth assuming it runs and the water pump works.