There is one available somewhere that looks the same as the original so there's no problem swapping it out. Check Classic Parts of America. I seem to recall them having a lot of heater parts. That's where I got the complete heater core for $200.
Ya. Just checked. They have a 12v that looks the same for $50.
1939 Packard Standard Eight Coupe (The Phantom) | 1956 Cadillac Coupe de Ville (The Bismarck) | 1964 Ford Galaxie 500 coupe |1966 Ford Mustang (Little Red) | 1969 Pontiac GTO (The Dishpit) I 1979 Ford F-100 | 1976 Ford F-150 (Big Red) | 1995 Ford F-150 (Newt)