My mistake, the three horse Elto Campsters used the wobbler/rotor style impeller and your motor uses a standard vein style impeller. It’s the same one used in the Johnson TN’s of the era and the P/N is 375688. Since these aren’t so easy to find anymore, a later 5.5 – 6 horse impeller, P/N 434424 or Sierra 18-3001, can be modified to fit. Here’s a link explaining how to enlarge the bore a bit so it will fit on your driveshaft.
http://www.pochefamily.org/outboard/ImpellerConv.html
