It's a clutch. I was looking for differences without opening up the cover. I noticed that when you take out the shafts that there is nothing obstructing the view on an lsd and there is on an open diff. I don't know if it's that way on all of them or not. Also noticed on the top of lsd that there is a small raised area about 1"X1" that is not on my open diff. Has anyone noticed this before. I can't figure out how the heck to post a pic or I would.