Beginning with the No. 50 Gang Car in 1954, Lionel would produce several others of this type of small unit. These units would be distinguished by their automatic reversing feature. They would run in only one direction depending on where the sliding directional plate on the unit was located. When it came to the end of the track, and struck a bumper, the plate would move, and the unit would reverse direction until it hit another bumper at the other end of the track.