Union Pacific was an early customer for General Electric’s new U25B line of 2,500-hp diesels, acquiring 16 of the units including the four demonstrators starting in 1961. Eleven had short high hoods, including the 629, which on October 13, 1968, rests between runs at UP’s Pullman roundhouse in Denver. The U-boats and their successors would go on to eventually challenge EMD hegemony of the locomotive market, but Union Pacific would skip the builder’s later B-B models, instead buying six-axle GE’s by the hundreds.
