Nice catch.  I saw two in action on freights, around 1974, but there was no chance for a photo.  (Not that it would have mattered, because I did not get a 35mm camera until 1975.)  The first encounter was at Washington Boro at night; the engineer was having a great time blowing the unusual Hancock air whistle.  The second time was near the Kellogg's factory west of Lancaster, where one was heading east with a Truc-Train. 
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