I have the 1978 edition of Northern Rails. Published buy The 470 Railroad Club. It states that the gauge is 18 3/4" locomotives are 3-ton Plymouth Model AL. SN 750 purchased 1919 and SN 895 purchased 1920. Original built with Continental 4's replaced with Chrysler 6's. For 1978 it states the locomotives are store, but cars are hand pushed.