I’ll go out on a limb and say it’s a ’39 Sea-King built by Thor for Montgomery-Wards. The ‘S’ kind of throws me off though as the Old Outboard Book says it should have a ‘W’ for Wards or ‘WK’ for Wards-Kiekhaefer for the later ’39 models. This is around the time Elmer was getting involved so maybe he let this one slip out the back door. Does it have the rounded skeg on it? Does it say Thor or Sea-King on the sheave cover? I believe the Streamliner was a ’39 one year motor. Teardrop gas tank?
It’s kind of hard to see but this ’37 Sea-King has the ‘W’ in the serial number.