I'm looking for thinly cut ribs for kalbi. Other stuff, too, of course, but mainly that. :^)
I usually go to the Oriental markets corner of Jean-Talon and St-Denis, but I haven't looked for the ribs especially. Maybe they're there?
There's a very large, terrific Korean grocery store on St. Catherine Street West, maybe a couple of blocks east of Atwater - sorry, can't remember the exact cross street or the name of the store. But they had all the Korean groceries items you could wish for, including frozen meats. I believe they also have a butcher counter right at the back.
The cross-street is Chomedey. One can't really miss it; it's on the north side of St. Catherine with a bright green sign, a shop or two away from La Maison Bulgogi.
I don't think they have a butcher counter, but they do have frozen cuts of galbi, sliced lamb and beef for shabu shabu/sukiyaki/hot pot, and even makchang (or is it gobchang?).