I am a bit confused what rear end my 09 R/T Auto has. It will lay down dual patches when doing a burn out but if I lift it up and spin the driver rear tire the passenger tire does not move. The same goes for the passenger side. I thought if it was an open diff the other tire would spin opposite direction? My Ram and my wife's Yukon have an open diff so the other wheel spins opposite direction. Is the rear end in my Challenger what they call a brake differential? I am a bit confused what it has .... build sheet just says 3.06 rear axle.