cleaner air package

Sure is helpful the imperial club shows the dates.
So now looking at the 1967 Plymouth Sevice Manual. It lists the "Closed Crankcase Ventilation" as all California and extra for other states (Lube and Maint chapter). It lists both standard and CAP ignitions for all engines. In the '68 book, there's a lot less engines with standard (non-CAP) ignition.