I see that there is an option for a locking rear diff? How is this different from other diffs?

 

A locking rear diff locks both sides of the axle together so both rear wheels constantly turn evenly, as opposed to other diffs that transfer most (or all) power the wheel with the least traction. What happens without a locking rear diff is if you have one wheel off the ground, then it will get all the power sent to it, while the tire on the ground that actually has traction gets no power. With a locking diff even if one tire is in the air the other will still get 50 percent of the power sent to it. The reason non-locking diffs are used is so as you go around a corner, the wheels can turn at different speeds (since outer wheel has to go father than inner wheel when making a turn. This is just a basic explanation, as these systems are much more complicated, and there are many variations of non-locking diffs.

 

http://auto.howstuffworks.com/four-wheel-drive.htm

Start Reading =) Hopes this helps

 

Thats a good site... anyway, I think its alot like posi-track if not the same thing.

 

Yep, it is very similar to positive traction.