have an 03 nav with limited-slip rear end.is this different then posi ?
because i know with the car on the jack and you spin one tire with your
hand one tires turns opposite direction . unlike my posi on my mustang.
is this correct? thanks..........

 

Here is a description I found that may help you..

Limited-Slip (or Traction Lok - the Ford name, or Posi-Traction, GM name) is a function of the differential allowing one wheel to spin only a percentage faster than the other. This has its advantages in allowing more traction, especially during hard cornering, because a normal or "open" diff will allow the inside wheel to lose traction and spin as fast as it wants, while the outer tire (with most of the traction anyway) just freewheels. This is generally opposite of what you want to have happen. A Posi unit will allow the inside wheel to spin only so much faster than the outside, at which time it transfers torque to the outer wheel, increasing power that's transmitted to the ground. This is achieved by several methods. The most common is with clutch packs in the differential that are set to a "breakaway" threshold. Another semi-common way is using viscosity (Viscous LSD's), which use a special differential fluid to control the amount of slip. A third method is a Torsen type, where there's a worm gear and pinion (the theory being the worm gear can rotate the pinion, but not vice versa). In effect, you can think of cars without Posi to be "one wheel drive" and cars with Posi to be two-wheel drive

 

The short answer is no. They are the same thing.

 

so should the limited-slip spin both wheel like posi-traction does?

 

What is your axle code?

These are the Navigator axle codes.
16 — 3.73 ratio, non-limited slip
H6 — 3.73 ratio, limited slip

By your description it would be non limited slip.