[blykins]

Yes, you're right....Posi & Trac-Lok are both trade names....However, both use mechanical ways of locking up....i.e. clutch packs & springs....

The LSD units could possibly use clutch packs also, but there are other types of LSD's that use a fluid to lockup....like a torque converter....or the central LSD on say an AWD Lamborghini or Porsche.

It's hard to be "politically correct" when describing this stuff. There's too many trade names and too many names of definition.

I guess all differentials that allow traction to be transferred to one wheel or both are all types of limited slip units....However, not all limited slip units involve mechanical friction...i.e. clutches, shims, springs, etc. as stated above. Some rely on viscosity...

I guess they all perform the same function....but in my mind, when I think of posi-traction (like a GM or a Trac-Lok) I think of clutches inside....when I think of a LSD unit, my mind thinks in broader terms.....