It's very simple. The small chebbie for example remained virtually unchanged from 1955 until 1986. The Chevrolet big block remained virtually unchanged from 1965 until 1986. Even after 1986, both engines had a LOT of parts that would interchange with the first generations.
That in itself is why Mopar people are special. It takes more work, more money and more dedication to build and own Mopars. The end result of that however is owning a muscle car that's head and shoulders above any other American automobile ever made. PERIOD.
