Caption: ALCO S-2 switcher CP 7042, is en route between its parking track beside the roundhouse, and a flat switching job in Trois-Rivieres yard, where it was regularly assigned. My source indicates it was built by ALCO Schenectady in 1946, so it was then about 24 years old.
I don't ever recall multiple switchers working together at T-R in 1970-71. The absence of MU socket and related brake hoses in this S-2 picture is one very good reason !

I was the only visible railfan around T-R station and yard for the two years we lived there. The local railroaders may have been puzzled by my activities, but were quite tolerant. I didn't push my luck too far, I guess.