You know how Kleenex is just a brand name for a type of facial tissue?
Thats how the name Positraction is to limited slip differentials.
The easiest way to install one is to swap out the entire rear axle with another one that has it in there. Otherwise you risk an opportunity to learn all sorts of details about shimming and how it relates to ring and pinion gears. Takes an experienced hand to do it right and avoid whining or excessive wear from the gears.