The ALCO Century 630 is a model of six-axle, 3,000 hp (2.2 MW) diesel-electric locomotive built by the American Locomotive Company (ALCO) between 1965 and 1967.

Montreal Locomotive Works produced a C630M variant of the C630, with 4 for British Columbia Railway, 8 for Canadian Pacific Railway and 44 for Canadian National.

MLW M-630s were built by Montreal Locomotive Works from 1969 to 1973: 29 for CPR, 26 for BCR, and 20 for Ferrocarriles Nacional de Mexico (N de M).

In January 1975, four Chesapeake and Ohio Railway locomotives were sold to Robe River Iron Associates in the Pilbara region of Western Australia.

One was destroyed in an accident in February 1979, with the remaining three rebuilt by A Goninan & Co, Perth as CM40-8s in the early 1990s.