The ALCO Century 628 was a six-axle, 2,750 hp (2,051 kW) diesel-electric locomotive. A total of 186 C628s were built between December 1963 and December 1968. There were 135 C628s built for U. S. railroads, 46 C628s were built for Mexican railroads and five C628s for Australia.
The C628 replaced the C624 (DL600C/RSD-41) as a part of ALCO's 'Century' line of locomotives. The C624 was intended to replace the earlier RSD-15 model, but was never built. The C628 was offered instead in August 1963.