About 30ft down the talus from the red wall chasm and towards Black crack if I'm remembering it correctly. There are two heavily chalked 'slopers on a face' problems on the outside walls (at the end towards Black crack) and an obvious cave with the crack in the ceiling. The crack extends up both outer faces of the cave.
Now I feel like an idiot (which is not to say that I am not one already)
I thought I know the Gunks fairly well and yet I have no idea of the place you are talking about. Just realized that I have heard of the black crack at LC... doh, that's what happends if you spend most of your time bouldering ... ok, i will check it out