What is a posi trac or limited slip differential?

Answer 1

A limited slip aka posi trac (chevy term) differential aka diff senses when your tires are 'slipping' more than they should for turning, and lock the wheels together, forcing them both to turn, putting more power to the pavement and letting your car accelerate faster, or helping you get out of a ditch or mud hole, the old style rear differentials were well know to leave you stranded in ditches and mud because which ever wheel had less traction would spin, and the one that had traction would 'slip', leaving you stuck. hope this helped with your question.