273 2 barrel air cleaner base

The lid is the same as used with a 1bbl baseplate on some '61-'69 Slant-6s, with or without the crankcase breather nipple, so at least there's that. But yeah, the 2bbl baseplate is the prize find, used only in Barracudas to provide an unsilenced air cleaner assembly. Non-Barracuda 273-2bbls '64-'69 got the kind shown by Magnum Valiant, with horizontal (old-fashioned clamp band) fastening in '64-'65 and vertical (wingnut and bail) fastening from '66 on.