slant six air cleaner position

'72 was the first year for the air pump ("smog pump") on Slant-6s, only in California, so yeah, this looks like a California '72 (with power disc brakes, which explains the air cleaner). That would mean it also has the godawful no-valve EGR system: a hole in the floor of the intake manifold that admits exhaust to the intake tract 100% of the time. While cranking, while idling, while cold, all the time. Requires high idle speed and causes rotten driveability. The car will run a whole lot better if you remove the carb, unscrew the floor jet from the manifold floor, and replace it with a correct-size plug.