There were 14 Hemi 'Cuda convertibles for 1970. My father in law was going to buy one of them new off the showroom floor in Seattle (one of the larger Chrysler/Plymouth dealers at the time.) He was going to trade in his '65 Impala SS Convertible. My mother in law told him they couldn't afford it, even though it would have only cost a couple grand out of pocket. (The 'Cuda had been at the dealer for a year or so without selling, so it would have been a great deal.)
He remembers it as being one of the 4spd cars.
Bummer, because it now would be a several-million dollar car. Instead, he still has the Impala SS.