Whats the difference between a 1975 3 cylinder 75 hp stinger and a 1989 3 cyl 70 hp motor internally? I know there is a bit more compression in the stinger but that is achievable with the head are the rods/pistons different? Can you run all the later ignition on the older motor?
Any help is appreciated.
What year did they change the hp rating from powerhead to prop?

Thanks in advance Bill