Denver & Rio Grande Western Railroad's 491 (4-8-2) makes an impressive plume on a bitter cold day as it runs the circuit at the Colorado Railroad Museum in Golden, Colorado. The engine was built in 1902 as a Class C-41 standard gauge locomotive. In 1928 she was converted from a 4 foot to a 3 foot gauge configuration. Designated K-37 class, the unique frame configuration had the driving wheels placed between the two chassis frames which support the boiler, but with the cylinders, driving rods, counterweights and valve gear located on the outside the frame. The K-37's were the largest operating narrow gauge steam locomotives in the Western US and worked in numerous mountain areas in Colorado.