The RDC (Rail Diesel Car) was manufactured by the Budd Company as a "self contained" passenger train. It was used by many railroads from Class 1 to tourist lines and many are still in service today. They ran alone or as multiple units.
The modification of a standard Eishindo KIHA mechanism to fit the RDC-1 shell is pretty straight-forward. In fact, the mechanism will work with the shell un-modified--but the truck spacing is not correct. One other note--If you don't have or don't want to chop a second frame, the parts can be made from styrene with a little more work. The following photos illustrate the process.