All Federal cars had PCV valves something? like 63?
In 66 CA required emissions on engines.
In 1968 ALL cars federally had emissions controls. Stuff like GM had "smog pumps" Chrysler got by for years by leaning out the carb and retarding ignition. For this reason lots of guys try to tell you "my car didn't have" emissions equipment. Well it DID, you just could not SEE it, LOL
In 72? EGR got added and for the first couple of years Ma used no EGR valve. Ma just drilled orifices down in the bottom of the intake manifold, causing a "controlled leak" between exhaust crossover and intake. So you could not "see" the EGR for a couple of years.
Emissions was constantly getting tightened up over the years, and every few years, CA and "the feds" added more and more requirements.
Starting in '70 CA required evap systems for fuel systems, AKA "the carbon can" This was required federally 71/ later.