Originally Posted by yulscs

YUL has only one terminal. I am assuming your TATL will be on a different booking from your US-bound leg, but provided you aren't checking bags, and have a boarding pass for the connecting flight, you should follow the connection signs, skipping Canadian border formalities and going to US CBP, and you should be able to make any of those 3 if your arrival was on time. (If you are checking bags and can't interline them, you have to enter Canada to collect and re-check them, and that would slow things down some.)

Edit: Apologies, just noticed you said you are checking bags. I guess check with your TATL carrier (you didn't specify) whether they'd be able to automatically transfer them in YUL so you can stay airside. For CBP pre-clearance if you have GlobalEntry that'll help.