M-10003 to M-10006
Streamlined trainserts used on the “City of Denver” service
The Union Pacific Railroad's M-10003, M-10004, M-10005, and M-10006 were four identical streamlined diesel-electric power car trainsets delivered in May, June, and July 1936 from Pullman-Standard, with prime movers from the Winton Engine Corporation of General Motors and General Electric generators, control equipment and traction motors. One was for the City of San Francisco, two were for the City of Denver, and one was a spare set intended for both routes. In 1939, M-10004 was split and converted into additional boosters for the other sets, now renumbered CD-05, CD-06, and CD-07, all running on the City of Denver. The M-10001 power car became the other third booster. In this form, the three power sets ran until they were replaced by E8 locomotives in 1953, at which point they were all withdrawn from service and scrapped.
Historical significance
The M-10003 through M-10006 represented the final development of the custom streamlined trainset on the Union Pacific. They followed the cab/booster unit concept pioneered with the M-10002 trainset. As totally separable and interchangeable cab/booster power sets, they set the path that EMC was to follow with introduction of their E series locomotive sets the following year. Union Pacific was able to maintain daily service on the Chicago-Denver run for seventeen years by dedicating three locomotive sets to that service and re-purposing power units from M-10001 and M-10004 (three total) to provide additional power and keep at least two of the locomotive sets in running condition at any given time.
Details
These power sets had stylistic elements in common with the Illinois Central's Green Diamond trainset, which was completed just previous to them.
The public source identifies “M-10003 to M-10006” as streamlined trainserts used on the “City of Denver” service. This brief keeps that definition visible, then builds a research path around M-10003, M-10006 and Streamlined.
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The strongest evidence will usually combine a dated visual record with documents produced by the authority responsible for the place. The source revision retrieved here is dated Aug 10, 2026. The linked authority identifier is Q6711929. None of the 0 selected statements returned an explicit reference. The first chronological checks are 1936, 1939 and 1953.
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This entry incorporates text from “M-10003 to M-10006” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.