50HP 2-stroke Can someone help?

[Tyson0317]

I have a 50HP 2-stroke Mercury outboard. It's got to be old. Inline 4 cylinder with 2 carbs. SN 4709813. Would love to know the model number and year of manufacture.

Thanks in advance!

 

[Tyson0317]

I just googled this. Cant find anything offical, but a chart I found says, 1977. REALLY!? Can someone confirm?