I have the Kato electrics, and the RSD, but don't know if they will work together. I've never had the two old electrics, an EF-15 and an EF-57, the Con-Cor model, apart. I did take the trucks apart to have the flanges turned, but was afraid to try to take the frame out of the body. Thus, I have no idea if the RSD trucks will go in.
The frames are held in by the windows, as far as I can tell, and after trying to get them apart by prying, I'm afraid I'll break them. Repainting into MILW colors was done by very carefully masking the trucks and windows.
Since the early RSD and RS3 trucks were interchangeable, if someone has the electric and the RS3, they could also answer the question.