I have 2 10 bolt rears, both with 7.5 ring gears. One has Posi, one is open. The Posi rear has shredded spider gears and I'm wondering if the spider gears in the open rear are the same as the ones in the Posi? I've called summit, jegs, JC Whitney, and they all seem to want to say they are different, but nobody carries the part to be able to compare.