I was replacing the rear fluid in the diff today and wanted to check the gear ratio on the ring gear. I had the car jacked up on one side as far as it would go wich brought the wheel off the ground so I could get to the bolts. Since the wheel was off the ground, I decided to spin it to check the ratio numbers stamped in the ring gear but it would not spin. I was like, oh yea, it is in gear, but then I remembered that one wheel should have been able to turn. I looked closer and saw the strange looking unfarmilier center carrier and I was like, sheeyat, I have a posi rear, no wonders the tire would not spin, but, it DID move maybe 1/4 inch in either direction. Hmmmm, now, I though that maybe that was the side carier/ pinion gear play, so, I took a peek in there and none of the gears ANYWHERE where moving, but, the tire WAS!?

How can the tire move on/with the shaft but nothing in the carrier that I could see moves?? You COULD hear something moving in there like there was some sticky substance moving around when I moved the tire, but, no visual movement what so ever........