CP Rail 8558, an MLW RS-10 (?) gets turned around on a chilly morning, 1966.

I can't say for certain, as I'm terrible at identifying locomotives! But I'm pretty sure this is an MLW RS-10. Montreal Locomotive Works (MLW) was a subsidiary of the American Locomotive Company (Alco), and produced locomotives primarily for the Canadian market. MLW operated from 1883 to 1985, before being sold to Bombadier Transportation and dissolved.