That is the engine found in the 1971 HEMI 'Cuda ... and '426 HEMI' boxes. Plymouth only produced 21 HEMI 'Cuda Convertibles ...
The Chrysler Hemi engine was ... alongside the Plymouth Belvedere. It's also one trim level down from the Dodge Coronet Super Bee, one of the rarest Mopars ever built, which can also be had ...