4-Door with 340 from the factory?

In the early 80s Larry Shepard told me there were a few B engine dusters built. I never seen any documentation on them. He was the Mopar god so I seen no reason to disbelieve him. I think maybe he meant the mule cars that had the DC K member that they put the 400 into and we’re testing cams, intakes and other performance parts. Kim. I just remembered that he said 1970 dusters with 383s. That’s is so long ago that maybe I’m remembering wrong.
But with a Dana Super tracknpak and a 4 Speed, I'd Be in Love!