[71chevylowrider]

If it's a standard GM 12 bolt rear end then if it is posi it will likely be an Eaton limited slip, which in essence is what we call posi, even though it's not a locker or a true locked type posi unit, it does do dual rear tire burnouts. Now, here's what they will look like. the pic is an Eaton Limited slip for a 12 bolt truck.