FYI, it is not an unsilenced air cleaner, and it was used on some but not all passenger car slant-6 applications from 1961 to 1969. The 1961-'63 covers have no crankcase breather nipple. The crankcase breather nipple first appeared in '64 on the California cars, then in '68 in the other 49 states and Canada. The '69 baseplates have a small nipple for the throttle plate anti-ice air inlet.
The same cover was used on the unsilenced 2bbl air cleaner on '65-'66 Barracudas, and (with chrome plating) on the 4bbl setup as well.
