From and SAE Transaction paper I found, where Chrysler presented their Clean Air System, which was "engine tuning" rather than "add-ons", starting in about 1966, then used a learner carb calibration, for normal driving rpms (WOT was allegedly not affected as the only emissions measurements were for what became known as "I/M 240", based on Los Angeles commuter traffic route), a slightly higher idle rpm and 14.2 air fuel ratio. Chrysler got their engines to pass with these fine-tuning issues, plus a few other little pieces of equipment in the mix. GM and Ford were using the Air Injection Reaction Pump system of adding extra air to the exhaust gasses to keep them burning longer (in the exhaust manifold). The AIR system needed a pump, hoses, check valves, and a switching valve to work. MORE expensive than the Chrysler system, which made the GM accountants mad, big time, so the story gores. It was mentioned that Chrysler's better combustion chamber design allowed Chrysler to do what they did, compared to what GM and Ford typically had.
'73 Chrysler products, in some cases, needed the AIR pumps, finally, as the regulations got tighter. Evap emission canisters had happened in '72. The "floor jet" EGR system was also in '73. The first thermo-vacuum switch operated EGR valves were in '74. "Hot Air" air cleaners, with the temp controlled flapper door, started in about '69 on most makes, which is also when Chrysler's air cleaners started having different designs than in the past.
The '75 B/RB engines with air pumps also used the short oil filter, rather than the prior long filter. The air pump belt necessitated that change.
Except for the 360 HO 4bbl, 400 HO 4bbl, and 440HO 4bbl all still had full dual exhausts, NO cats, in '75 and '76. Basically, the law enforcement "fleet" engines, plus a 381 2bbl non-cat motor. All could still use low-lead fuel, if available. Initially, cat-equipped cars weren't allowed on some federal lands due to the hot exhaust and potential for grass fires. Chrysler's converters had "environmental heat shields" hanging below them. The bottom of the GM converters had some sort of heat insulation in them, with only underbody floorpan heat shields. All cat converter cars had those underbody shields from the converter forward, or "muffler forward".
The Lean Burn 400s came out in '76 mid-year, I believe. Non HO engines, but non-cat single exhausts. Back then, near the door latch on the lh frt door, there was a sticker "CAT" or "NON CAT" to designate what the car was supposed to have. Different colors, as I recall. Seems that like the Cordobas I saw that way, the words had a Maple Leaf surrounding them, as they were built in Windsor, for the USA market?
But by '77 MY, the USA emissions standards had tightened enough that cat converters and AIR pumps were on everything. The police-spec dual exhaust engines were REAL dual exhausts with dual cat converters. Unlike what GM did with a single converter that split into a "dual outlet" single exhaust (as the '77+ Z/28s were).
The various engines might have had some similar equipment on them, but it was not "identical-spec" equipment in all cases. What was on a 360 might be similar to what was on a 400 or 440, but with parts calibrated for those particular engine sizes. "Application specific".
In the USA, there were "Federal" specs (which was the "normal" stuff), "CA spec", which was unique to California, but could be special ordered for delivery/sale in other states, and "High Altitude", which was related to states like Colorado. All unique carb/ignition calibrations.
I have no specific knowledge of what Canadian emission specs might have been back then, but considering the nearness to the USA, I suspect the Canadian emissions specs might have mirrored the USA "Federal" specs. Just my suspicion. This would be for "passenger car" applications.
The USA light-duty trucks usually used car-spec engines but didn't need cat converters unless they had a GVW of less than 6100lbs. Above 6100 lbs, no converter and fuel nozzles that would accept non-unleaded gas pump nozzles. Until about 1980 MY. But would still have AIR pumps and EGR valves. Once the GVW got past 8600lbs, that was "HD Emissions" that were exempt from measurement, as I recall, but they still had much of the same 6100lb+ items on the engines.
Hope this might help,
CBODY67
