Love the "old" pictures, John. IYDM, a short story.
According to all the references, the GM&O was fully dieselized in 1947. But I know that in 1957, it had at least one active steamer on one day. I was visiting my cousins in the town of Centerville, Al (it was on the GM&O main from Montgomery-Tuscaloosa), and we were taking my uncle his lunch one day at the Belcher Lumber complex there.
My cousins lived only 2 blocks from the mill so we walked to there, and while we were there a GM&O local from Tuscaloosa came to the mill with about 10 cars. Pulling it was a small steam switcher, an 0-6-0. It was lettered GM&O, (according to my Mom, who was with us kids), and sounded like it was on its last legs.
It was the only time that I ever saw steam running in revenue service. I must have loved that sound, as I have been a steam freak ever since.
I wouldn't see another steamer running at all until the excursions started up on the Southern about seven years later.
Why that loco was running that day, I'll never know. It must have been due to a power shortage in the area. At that time, and at my age, I was used to seeing 4-5 "red trains" running there. I would later find out that they were the ALCO Rs-2's that frequented that line for many years.