I don't want to start a big pissin match but there are differences between a GM (Eaton) Positraction and any other clutch type limited slip differential. The Eaton Positraction is the only one to apply more clamping force on the clutches as torque is applied to the driveshaft. That's why GM's don't have problems with 1 wheel wondering with a posi where the Fords LS diff. may have those problems from the factory oke:1040 WreckerMan said:A posi and limited slip are the same thing. Positraction was a GM brand name and it was a clutch type limited sliff diff. No, not all trucks came with LS diffs. What it would cost to swap depends on what you want to go with. D you want another clutch LS, Gleason type LS, etc.
If you are paying a shop to do the swap you'll probably be around 800 depending on the type of LS you choose.