I often see posi's for sale on e-bay that look like this. From the picture, how can you tell this is LS? Looks like an open diff to me . . .

 

Good question. That's what mine looks like and my axle code says LS/3.73. If I jack up the rear and spin one rear wheel forward, the other will spin backwards which looks like it's open. It acts on the street like a LS. The only thing might be that the clutch packs are between the side gears and the case which makes them hard to see. Hopefully someone will be able to explain it.