Technical Rear end

Is a 1956 Olds rear end posi

 

posi was only optional, not likely. gary

 

I don't think any posi was available before 1957.

 

Easy to check, just rotate one side drum, and have someone hold the other side still. If your side is easy to turn and pinion turns, it is open. If the other side wants to turn same direction as yours, it might be limited slip. Could also be stuck, with small corrosion inside, so turn it hard to see if it breaks free.