Total BS !
Positraction Differentials
A positraction differential is a special traction differential. Its purpose is to improve the way your differential performs under adverse conditions. When one wheel starts to slip, these differentials transfer the torque to the wheel that is not slipping. The car can then continue to go forward. There are several different kinds of positraction differentials, but all of them are based on a friction device to provide resistance to normal differential operation.
A positraction differential provides better traction, which is handy when roads are slippery. It also lends itself to fast acceleration.
The same as a Trac-Loc, limited slip !!
I had plenty of chevys to know !