DF-Prints. Here is a print by an unidentified photographer that was taken near Perdix, Pennsylvania, c. 1966. Shown here (L to R) is Pennsylvania Railroad engine #2439 and two more units whose road numbers are not recorded. #2439 is an AF-25 built by the American Locomotive Company in December of 1965 and rated at 2,500 horsepower. In this context, they're passing under four-track Signal Bridge 1142/3 with a mixed-cargo freight train out of Enola on its way to Altoona and points West. A snow-covered Blue Mountain dominates the distance. Brad Mann Collection.