I used a flywheel (with ring gear) from a 1960 Jonson 18 Hp and used it on a 1967 Johnson 20 hp, with an electric starter and bracket. Worked fine. I have also used 50:1 on a 1959 Evinrude Big Twin for 20 years. In 1964 OMC went from bronze bushings on small engines to all roller/needle bearings...
