 Late SW1200s built in 1966 were built with the 567E 12-cylinder engine.Additional SW1200 production was completed by General Motors Diesel in Ontario, Canada, between September 1955 and June 1964.737 examples of this locomotive model were built for U.S. railroads, 287 were built for Canadian railroads, 4 were built for Brazilian railroads, 25 were built for a Chilean industrial firm, and 3 were built for the Panama Canal Railway.