Year of 50 hp Mercury outboard

Trying to find out the year of a 50 hp mercury outboard motor I got the serial #A159659

Pictures of motor and serial plate.----------3 or 4 cylinders ?

Rautin said:

Trying to find out the year of a 50 hp mercury outboard motor I got the serial #A159659

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I have a similar outboard with a similar serial number that I got with a recent boat purchase.
Wanted to know if this was a good investment to get it running.
Mercury 500 thunderbolt 50hp serial # A130682
The lower unit decal is a different color than the powerhead. The lower is orange & white, while the upper is blue & white. Could a different year lower be mounted to to a different year upper? This engine has a rope starter, cable operated steering. Provisions for a starter but lacking the ring gear. the starter has round mount on top but the bottom has two threaded holes. I will post photos. 4 cylinder, 2-stroke.