To point out: Although this LOOKS like a PRR K5 Pacific, what with the casing behind the smokestack and the front-mounted, highly-polished brass bell a la K5, this appears to be neither 5698 or 5699--subtle differences abound. I've spent the last half-hour going through my PRR loco books and am befuddled, being unable to come up with a regular K4s with a front-mounted high-polish bell. Possibly a mis-labeled photo of a K5, with the aftermath of yet another rebuild?

Definitely a K5, 5698 to be exact. The main difference in spotting 5698 and 5699 is the length of the smokebox. 5699 had a much longer smokebox, giving a "leaning-into-it" look. Origininally 5699 was equipped with Caprotti poppet valves, but these were removed and Walschaerts installed.

Members of the PRRT&HS say 5698 as well, possibly Pittsburgh in the early 1930's. The bolts on the side of the steam chest seem to confirm this, though the side footboards don't match any of a dozen or more photos I have.

I wonder how it got mis-labeled as 5590?

Probably the numbers on the original print aren't very clear. The posted scan is terrible.

FWIW, the two K5's were assigned to the Northern Central section of PRR out of Baltimore, right in your back yard IIRC, and through York, my home town.

According to "Pennsy Power" by Staufer, they were originally assigned to Philly-Pittsburgh trains, then to the Northern Central, then finally to Pittsburgh-Crestline. Given that this appears to be an earlier photo sans modifications appearing in later photos, I'm inclined to agree with the Pittsburgh location nominated by the PRRT&HS members.