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.
Look how clean that beauty is. Like a plastic model before it's been distressed.