We're deep into the PRR steam era from the Dziobko camera. Assuming the date on the slide is the date the photo was actually taken, it would seem to contradict the late Don Ball, Jr., in his book "The Pennsylvania Railroad 1940s-1950s". He wrote that the last steam movement on the PRR was on Nov. 27, 1957. (Cresson-Altoona run). Seen here PRR Class I1s. Anscochrome film.