492-0051 means a 1935-36 Sea King model 8802 of 8.5HP, but the book says a 492 could also be a 1937-38 Sea King model 8808 of 8.5HP.. The 0051 is just the serial number. Check for either of these 88xx numbers on a welch plug on the powerhead. Possibly try to find motor pictures from those Wards catalogs showing decal pictures. Or contact the Sea King special interest group leader for info.