1955-57 Pontiac Heater Core Connector Price $39.99 Prev Next Product Description In 1955, 1956 and 1957 Pontiac placed a return fitting from the heater core to the lower radiator tank. We put it there when we build them, but most radiator manufactures do not install it. We came up with a lower hose in-line fitting that accomplishes the same thing. 1-3/4" tube unless otherwise specified at the time of the order. Made in the USA.