What is the difference between posi and limited slip? If someone could explain this or give me a link that would be great. Thanks

 

They are one and the same. Posi is a marketing name Chevy adopted for their limited slip. Actually it was called PosiTraction. There are different types, but they all accomplish the same thing. Eaton uses springs and clutches, Auburn uses cone clutches, Torsen uses worm gears. Here are some links.

http://torsen.com/products/products.htm
http://auburngear.com/

 

Which one do you think is the best/most reliable?

 

Torsen is the best in the drivability/reliability category since they use a gear drive rather than clutches. Only in very extreme situations do they fail or give poor torque transfer.

A clutch type (Eaton) is good but preload can be a problem on lesser units causing unequal torque transfer. Most of these types can be rebuilt also.

Cone types (Auburn) are relly good also but also like the Eaton the non heavy duty units can yeild poor torque transfer. They also are not rebuildable. Auburn also makes several heavy duty applications for F-Bodies.