This is fascinating! And too bad I didn't get to see the photo myself.
In studying my NYCRR Harlem Div. books there are sample photos of steam powered powered passenger trains dated all through the summer of 1952 right up to the last run of steam on Sept. 11. And, oddly, not a single photo of a diesel powered passenger train iin that period.
There were diesel powered freights (the "Rut milk" being a prime example) as early as 1950.
So why am I so interested in this subject? Well, the Harlem was my only physical contact, ever, with any steam in ordinary daily service, and it was about 1951, when I was 5, at Brewster NY. Despite the early age I remember it like it was yesterday. As you can imagine the sheer size was unforgettable to a 5 year old. Just the drivers on those NYC K-11s were quite a bit taller then my own size at the time. -Tom