Santa Fe 2099, the railroad's only Alco RS-2, rests at the Denver terminal in August 1957. It was built in 1950 as Alco's demonstrator 1600, was purchased by the Toledo, Peoria & Westerm, and was acquired by the the AT&SF the same year as its No. 2110. In 1952 it was renumbered to 2099, and in 1969 it was retired. The unit was equipped with a steam generator and dual controls, allowing it to operate with either end as the "front." When I took this transparency the short hood end was the "front," as indicated by the zebra stripes that point upward. Although equipped for multiple-unit operation, No. 2099 had to be the lead unit in such a consist because it had only a manual transition between series and parallel operation. This photo appears in Santa Fe Railway Diesel Painting and Lettering Guide for Model Railroaders by Stephen M. Priest, published by Paired Rail Railroad Publications, Ltd. in 2014.