As noted the D501s were a VERY limited production car, but their existance has been pretty well documented and as I said were powered by the Chrysler 354 "300B" engine.

Since I originally wrote this I have not come across any further information indicating there was any other "cross-breeding" between the different Chrysler division (not saying it didn't happen, just never have run across anything that is reliable documentation indicating it happened).

As I also mentioned even though the almost nothing is interchangable between the 3 divisions engines themselves, the entire engine assemblys are close enough to make the Hemi a virtual bolt-in into another car.