Summit part number: PLI-399043 DOES NOT fit the 66 Beaumont.
I'm back to looking for new core. I would consider re-coring my old one, but the failure was in the tank (the end around the inlet & outlet), not the core. There's a fair bit of corrosion on the tank and the metal is very thin.
I guess I'll be picking up the 9.5 inch long 'replacement' core. Anyone got a sketch of how they shimmed the shorter core so it seals and fits tight?