Model number J20ELCCA is a 20 hp Johnson outboard, electric start, long shaft, 1988 model, outboard engine.
your Johnson is a 1985 year model
Your motor is a 1955 model.
The letters in the model number designate the year model, when compared to a model / year guide.
6420800
The year model of an Evinrude outboard cannot be determined from the serial number, but rather from the model number.
The year is 1992 -the "en" in the model number identifies the year.
2004
1988
A 40 hp Evinrude, model number E40TELCO, is a 1985 year model.
You need to specify a model and model year, and also keep in mind that there was probably more than one motor option for that model year.
The year model of an Evinrude outboard engine is determined from the engine "model number", rather than the serial number.
1986