RS-18
MLW also introduced the 251B engine in late 1956 and put the 12 cylinder 1800 hp version in the RS-10 carbody to produce the uniquely Canadian RS-11M (later renamed RS-18). CN purchased 131 units between 1956 and 1958 and numbered them 3615-3745 (MR-18b, c, d). In 1959 they purchased 30 more units fitted with a steam line (but not a steam generator) and numbered them 3100-3129 (MR-18e). Finally a further 64 units were purchased in 1959 and 1960 and were numbered 3830-3893 (MR-18f, g).