A: Limited Slip (LS) is a traction aiding device that is in the rear differential. The stock LS is called Trac-Lock. It is an option only for the rear axle. What it does is keeps one wheel from spinning while the other sits still. It uses friction plates to reduce the difference between the 2 axle shafts, and does so automatically. But as the name implies, there is still some slip that occurs. It is considered better than an open differential (no traction assist device), but not as good as a locker.