I did. Emission and safety standards began to take hold in 72'. Hence the 400 "smog" big block. Even my 71' has some vapor lines from the gas tank, some kind of canister below the battery tray, and noise reduction package indicating pre emissions before they were mandated by the federal government. This is on my car because it was built to california standards and sold in california.

That's why most enthusiasts of ford, mopar, and chevy recognize 71' as the end of the muscle car era.