what pulled the overland express whne the cars were grey steam? diesel? and what configuration were they?
What do you know about this “Overland Express”? What railroad, what part of the country? What era? Many trains with a particular name were pulled by various pieces of motive power, depending on what was available…what do you know about this train already?
The Pacific railroad aka the Transcontinental Railroad, built by Central Pacific and Union Pacific, was sometimes known as the “Overland Route” and the mail train on that route was sometime known as the “Overland Express” but I assume there might be others…