Maybe it's just me or the part of the country I'm in, but you don't see any "older" air cooled outboards still running around here. I know they made them back in the day cause my dad use to have one. I remember the pieces of it laying around his shop after it quit running. I also haven't noticed any "older" ones for sale on craigslist or other places. To me, that suggest they don't have a very good life span. On the other hand, I see mid 60's and up model 4 to 8 hp two stroke water cooled outboards quite often. They may run and perform great when new, I really don't know, but it's apparent to me they aren't very durable.