The old Carpenter Steel Co. (now called Cartech) in Reading, PA had a fairly extensive two-foot gauge operation into the 90's. They had a fleet of 12, 15, 25, and 40 ton GE and Plymouth diesels that handled four-wheel flat and dump cars around the mill. When traveling the Route 61/422 by-pass around Reading, you could look across the Conrail/Reading tracks and see 2-foot track all over the place. It's all gone now. The WW&F and Maine NG both have ex-Carpenter locos, and I believe there may also be one or more at Edaville. Edaville got their first one in the 70's, I think. Brookville made/makes locos as small as 1.5 tons, as did Plymouth and Milwaukee..