I have the same heater as you, John. I ran the supply hose from the TStat/head to the lower nipple on the heater core.
I ran the return hose from the upper nipple of the heater core to the water pump.
Most vehicle heater core use the lower nipple as the inlet and the upper nipple for the outlet.
1950 Chevrolet 3100 (Ol' Roy)
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)
