Electric Rear defrost?

the only thing i can tell you is about the rear defrost. I have rear defrost on my 72 duster and if the 75 dart has it in the same place it will be on the bottom edge corner of the dash to the left of the steering colum. as to what it looks like its basically a chrome three position toggle switch attached to a black plate that reads Rear Air. hope that helps a bit.

if I find a pic I'll post it.