I need help identifying this motor. I have no experience with Mercury’s. I picked this up for a very low price, and was told it was a Mark 20. But I bought a mark 20 medallion and it is only a faceplate and does not wrap up to the top of the motor like the larger Mercury’s. Here are three photos. The serial number puts it as a 1953 Mark 20. But again the medallion has me stumped.