One of the earliest trains using remote mid-trains out of Andover, VA eases along through Appalachia, en route to Bulls Gap, TN. The receiver car was built on the frame and trucks of a retired FM road switcher. These early cars were soon replaced by custom-built receiver cars. Back in the day, the now politically incorrect term "slaves" was used to denote the mid-trains on the Southern. Today, of course, we know them as DPUs (Distributed Power Units).