I have a 20hp Mariner Ser#7224445. I've tried marinshopen which left me a little confused due to the language barrier. On that site it would seem the motor is a 1979 which still confuses me because I have 25 Merc which is either a 99 or 2000. This Merc is identical to the Mariner except for colour and decals. I just recently aquired the Mariner and it doesn't look like 20 year old motor. If it helps the motor is charcoal grey with a yellow, orange purple strip and mariner in white block letters. confused looking for help.