I just bought a 1965 Thompson and the previous owner put a Merc short shaft on it (and proceeded to cut the transom with a jigsaw to do so, but that's another topic). I need to replace it with a long shaft O/B but need to find out what this engine is worth. Someone told me it might be rare? The cover plate says "Merc 700", serial # is A-1415247 and it's a 70hp with a 22" (I think) short shaft (how exactly do you measure the shaft?). I would like to find out the year and approximate value, or any rading partners-we'd like to find a classic motor to go with the boat. I appreciate the help.