That is really cool, DieselDartGuy. I didn't know that Mopar ever sourced a Nissan diesel engine, let alone that they offered it in a Dart.
Chrysler must have been pretty hard up for diesel engines when the gas crunch hit in the '70s, because they sourced another diesel engine, this one from Mitsubishi, which they offered in Dodge pickups in 1978. It was expensive, and a flop, and only lasted one year, IIRC. It was a real dog and made significantly less power than the slant 6, and the slant was available for far less money than the diesel, so hardly anybody bought them. Just about the only Mitsubishi diesel pickups Mopar sold that year were for airport tugs and the like.