 All cars were equipped with GE 1259 DC motors with a rated output of on all axles.The M2 "Cosmopolitan" series (numbers 8400-8849) replaced EMU cars dating from the early 1920s to 1954, including the Pullman 4400-series, which were originally manufactured for (and inherited from) the New York, New Haven and Hartford Railroad.As with the cousin M1 series, the M2s accompanied an overhaul of the long-neglected main line and the New Canaan Branch in which longer, high level platforms were introduced along with other infrastructure improvements.