The Alco 539T is a diesel prime mover design built by the American Locomotive Company. This engine was also used as a stationary powerplant, used in pipeline pumping stations, tugboats and dredges. It began as a straight-six, four-stroke design in a cast block which produced from 810 to 1,000 horsepower. The engine has a bore of 12.5 inches (318 mm), and a stroke of 13 inches (330 mm). The 539 engine was built at Alco's Auburn, New York engine plant and later starting in September 1949 in Canada. The 539T was equipped with the Buchi turbocharger, being made under license by the Elliott Manufacturing Company of Jeannette, Pennsylvania. The first 539T engines were used in S-2 switchers and DL-105 passenger locomotives built in September 1940. Alco locomotives using this engine include the S-2, S-4, RS-1, RSC-1, RSD-1, DL-105, DL-107, DL-108, DL-109, and DL-110. MLW locomotives using this engine include the S-2, S-4, S-7, S-12, RS-1, and RSC-13.