B unit
The ALCO FA was a family of B-B diesel locomotives designed to haul freight trains. The locomotives were built by a partnership of ALCO and General Electric in Schenectady, New York, between January 1946 and May 1959. Designed by General Electric's Ray Patten (along with their ALCO PA cousins), they were of a cab unit design; both cab-equipped lead (A unit) FA and cabless booster (B unit) FB models were built. A dual passenger-freight version, the FPA/FPB, was also offered. It was equipped with a steam generator for heating passenger cars.