1987
1988
From what I can find in serial number tables, your outboard is made in 1975. My refernce: http://www.marinshopen.se/Hj%c3%a4lpmedel/Modellguide/Mercury/3565Hk/tabid/107/Default.aspx
Usually the serial number is on a tag mounted on the bracket that holds the outboard engine to the boat.
1985
How old is tohatsu outboard M25A serial number 34166
The 20HP Mercury outboard with serial number 9137627 was made in 1979.
whats the serial number
A 9.9 hp Mercury outboard, serial number OB235459 is a 1988 model.
A 35hp Mercury outboard, serial number 6445947, would be a 1984 model.
Two items are needed to determine the age of a Mercury outboard, the serial number and the horsepower rating.
In addition to the serial number, to determine the year model of a Mercury outboard, the horsepower rating is needed.