In the late 70’s, some trucks were exempt from all emissions controls if they had the correct suspension combination. These were classified as industrial equipment.
I once owned a 1977 Dodge truck with this classification. I bought it new. It had absolutely no emissions controls. The owner’s manual recommended leaded fuel. It was faster than many of the muscle cars of the day.
I had a friend who bought almost the same truck but with all of the required emissions equipment. Even though his truck had a larger engine, my truck would out perform his truck and used less fuel in the process.
In the late 70’s Dodge exploited this exemption about as far as they could. They had the Little Red Express and the Warlock series of truck. With each truck they must have cleared out all of their old stockpile of muscle car parts. The Little Red Express has a 360 with a lot of 340 Magnum muscle car parts. The Warlock had a 440 with a lot of 440 Magnum muscle car parts.
Ford and Chevy never took things to the extreme that Dodge did. But they also made V8 trucks without emissions controls during the late 1970’s.
one tons (C30) did not have cats