Unique Canadian National Locomotive Sighting

I saw a unique locomotive on a Canadian National Train I've never spotted before. The train was louder than the bell, you can faintly hear a unique bell on the train. Normally the locomotives have 2 windows while this one had 4
Usually, any locomotive I've never/rarely seen is "unique" in my book.
I am a Chicagoland railfan.I film the trains in Chicago while I am making my way. Sometimes I'll catch some rare/unique trains, locomotive bells etc.
I don't know a lot about trains to explain the things in my videos
I've rarely spotted a Canadian Railroad in the US.