The ALCO Century 630 was a six-axle, 3000 horsepower (2.2 MW) diesel locomotive built between 1965 and 1967. 77 were built: 3 for Atlantic Coast Line, 4 for Chesapeake & Ohio, 8 for Louisville & Nashville, 10 (with high noses) for Norfolk & Western, 15 for Pennsylvania Railroad, 12 for the Reading, 15 for Southern Pacific and 10 for Union Pacific.

56 C630Ms were built in Canada by Montreal Locomotive Works from 1967 to 1969.