World’s largest diesel locomotive In very much spring-like weather for Wyoming, with threatening clouds and a dusting of snow, an eastbound Union Pacific freight approaches Laramie in April 1984. On the point is the world’s largest diesel locomotive, the DDA40X “Centennial.” At almost 100 feet long and 6600 horsepower, only UP had them, and a few came out of storage one last time in 1984 and early ’85 during a increase of traffic.
