273 Radiator for 340?

A CAVEAT........and I'm convinced this happened to me

OLDMANMOPAR originally posted this, he claims he has found cases that make "sense" that years of thermal cycling have cracked the fins partially loose from the tubes. This causes the radiator to NOT be able to "radiate"!!!! The tubes can be brand new and flow like mad, but don't reject heat as they should

So..............the original rad out of my 67 273 WOULD NOT cool my pretty much stock 360. A rad shop claimed it should "cool anything." One day I had a /6 later model (73?) in unknown condition. Decided to swap it in "just to see". It was similar 2 core, the old 273 was round tank, the /6 was the newer square top tank.

THE TEMP IMMEDIATELY took a nosedive, obvious on the gauge and "feel" under the hood. It was DRAMATIC with no other changes!!!