My understanding is that the entire slide that looks like an upside-down Y is the Ribbon-True North Slide. When you head up the Orebed Trail, the first major brook crossing you come to after the leanto is the one you want to take. As I recall, it's .45 of a mile past the leanto. The brook splits, with the right branch heading to the base of the North wall, while the left branch , I believe, heads to the bottom of the longer slide leg.(the one with the island) It can't be more than 200 yards from the Orebed Trail.
The right branch will take you to the base of the Northface wall, which is a very impressive site. If you do take the right branch, follow it as close to the cliff face as you can, before turning left through the woods to pick up the shorter branch of the upside-down Y. I exited the drainage too early and got beat up by the cripplebrush. The slide in the lower right corner of your photo is the one that crosses the Orebed Trail farther up.
I recall someone saying that if you do head up the left drainage, keep a sharp eye open for the beginning of the longer leg of the slide. If you miss it, and continue up the drainage, you will hit that slide in the upper left corner. As you can see, it peters out on the flank of Armstrong. This is the slide that I thought might be called the Ribbon slide, but again, I doubt it.
Since Darren started this new format, it must not keep any of the old threads. I put a search in for any threads on the subject, and the only mention it has are within the last couple of weeks. When I was looking for info this past summer, there were some replies that had links to some fantastic aerial photos, and some ice climbers pics. Great stuff, hopefully, they will chime in and link them for you.
Washington is 20 minutes outside of Pittsfield, so the ride to Exit 30 takes about 3 1/2 hours with stops, not too bad. My sister is a nurse at BMC.