I just purchased one of these and according to the Marine Dealer that sold it to me it is an 1985 9.9 HP.
The Evinrude E10RCOM with the serial number E4078320 was manufactured in 1979. The first letter "E" indicates the brand Evinrude, and the following characters indicate the model and specific production details. The serial number can be cross-referenced with Evinrude's production records to confirm the year of manufacture.
An Evinrude outboard, model number E185TXCRS would be a 1984 model, 185 hp.
Model number 6303, would be a 1973 year model, 6hp Evinrude outboard.
A 15 hp Evinrude outboard, model number E15BACEC, would be a 1989 year model.
A 15 hp Evinrude outboard, model number 154040 would be a 1974 year model.
Model number E30ECRR, is a 1984 model, 30 hp Evinrude, electric start outboard.
An Evinrude outboard, model number 35853R, would be a 1978 model, 35 hp.
Model number E25TELCSA, is a tiller electric start, 20" shaft, 1980 year model, 25hp Evinrude outboard.
A 70 hp Evinrude outboard, model number E70ELCO, would be a 1985 year model.
The horsepower for an Evinrude outboard, can be determined from the engine model number.
A 40 hp Evinrude, model number E40TELCO, is a 1985 year model.
In order to determine the year model for a Evinrude, or Johnson outboard, the engine model number is used.