What, exactly, does this do? I've had 4x4s (K5 Blazer, Toyota pickups, CJ 7 Renegade, Xterra) all RWD and never had such a device.
Here's what I understand. Traction control detects slipping, and automatically cuts the power to individual wheels, where stability control detects slipping and applies brakes to individual wheels.
AFAIK, there are a few different systems in play on many modern vehicles, including antilock braking (ABS), traction control, and stability control (ESC). ABS modulates the braking to prevent wheel lockup. ESC controls individual wheels to help keep the vehicle on track. And traction control uses individual brakes to stop wheels without traction from spinning, thus maintaining torque to the wheels with traction; it may also cut power to prevent those wheels from breaking traction.
