Locomotive #6936 – DD40X

Union Pacific (UP) #6936 is a DD40X built in January of 1971 in an order of 47 units numbered 6900-6946 and classified as the largest diesel locomotives ever built. They were nicknamed Centennial units because the first one built came out on the 100-year anniversary of the construction of the Transcontinental Railroad. They are actually two engines on one frame, delivering 6,600 horsepower and built exclusively for Union Pacific.

#6936 is the only one left in operational condition. Working in regular freight service for the UP until making its last revenue run on May 6, 1985. It was then put aside and used for the UP excursion fleet. Running in excursion service and the occasional freight for the UP until its last run pulling the Cheyenne Frontier Days special with the UP E9 units in 2015. It was used one last time to help UP #844 during its test run on July 12, 2016.  Afterwards, it was stored at the Cheyenne roundhouse until being donated to the Railroad Heritage of Midwest America in April of 2022.  Read the complete article on the Union Pacific donation of #6936 here.

As of the summer of 2023, #6936 is fully operational thanks to the RRHMA now plans to use it in excursion service in the future along with special events.