|Zak. Here is a duplicate 35mm color slide of a photo by Martin Zak that was taken in Chicago, Illinois, perhaps during 1960. Shown here (L to R) are Pennsylvania Railroad engines #5901 and two more "EP" Class units whose numbers are not recorded. All were built by GM-EMD. #5901 is an EP-20 built in September of 1945, rated at 2,000 horsepower, and presently on display at the Railroad Museum of Pennsylvania in Strasburg. In this context, they're departing Chicago's Union Station with a passenger train bound for New York City.