It is a 1956. As noted, great running dependable. Will run super slow and quite. I am working on a ’61 LONG shaft. Low on comp but I will fix it and it will go beside the 850 Merc on the clipper. I have 5 of 3hp at the moment.
Just don’t go backing off the Mercurys Dave, I may need you again. 
AKA Outlaw Outboards in Fallon, Nv
Now in Twain Harte, Ca