Re: Best years for OMC 10 horse?

[Don]

Yes, there was a change to the driveshaft and pinion right around 1960. The earlier models had pinions that were keyed to the driveshaft, later models had a splined connection. Both style driveshafts are hard to find, and used ones are usually worn in the area I mentioned.
Both style driveshafts were usually ruined by lack of oil/water intrustion causing the lower pinion bushing and driveshaft mating surfaces to get worn excessively.