These carburetors were developed by Holley for Ford to use in NASCAR racing, when the NASCAR guys had to go from big blocks down to small blocks.

https://www.ford6vcarburetion.com/ford-6v-tech/

You can see in the story here, that NASCAR banned them before Ford even got them on the track. Ford scraped their program, which left Holley with a fully developed mechanical Six Pack and no customer.
They offered them to GM and MOPAR. GM said no, MOPAR said yes. The Carburetors were then sold through the Direct Connection program.

Robert