your problem is not having a complete core, with tank ends, to be rebuilt, the reason the cores aren't available is they're rebuildable if you have the tanks ... FWIW,
this core is 7.25" x 5.25" x 2.5" [without tanks], but note that the core tubes do not line up with the case holes, it requires the Ranco valve and rubber elbow to get there .... the thicker cores are from the cheapest dealer installed heater or from a 55-7 car heater
Bill
