The letters in the model number designate the year model, when compared to a model / year guide.
1969
1986
1980
1972.
Model number J150OLEVR is a 1997, 150hp Johnson outboard.
That in for a 1984 Johnson 70 hp outboard engine.
Johnson outboards uses the engine model number to determine the year model of the engine.
CD 24 is a 1967 model.
The year is 1992 -the "en" in the model number identifies the year.
1965 18 hp
The year model for a Johnson outboard is determined from the engine model number, rather than the serial number.
A Johnson outboard, model number CD-15, would be a 5.5 hp from 1958.