Posi/Non-posi
Veronica,
Yeah, there's a real easy way.
Jack up the rear end. Make sure both wheels are off the ground. Place jack stands under the car!!! Turn one of the wheels with your hand. Look at the other wheel. If the two wheels turn in the SAME direction, it's a Posi; if the two wheels turn in OPPOSITE directions then it's a Non-Posi ( open rear).
Jay67fast