One thing I forgot to add last time, when replacing the Pinion seal make sure and use rtv gasket maker on the outside metal frame of the seal before installing. I can't tell you how many Pinion seal leaks I've found that were not from the seal contact area but the outer edge of the metal to metal contact area, Also be sure to remember and mark the Pinion nut and count or mark threads and only tighten a little past or you will smoke the gears, It is normal for a Safety trac or Posi rear to turn stiffer in neutral then a standard Diff. a little backlash between the ring and Pinion is normal. On the 8.2s I normally find the numbers stamped from the factory such as 37-11 on the side of the ring gear. I don't remember seeing the scribed markings in your picture but may be my memory. I can't make out what it says by your pictures but may be a sign of an aftermarket gear set. To count the Pinion teeth you need to clean off the face and reach in with needle nose or grabber tool and mark a tooth edge then it's easy to count from their. You are right on the assumption of it being 3:36 with a 37 tooth ring gear if factory and it has a 11 tooth Pinion. It's hard to tell from the pictures but it looks like a 4 Pinion to me just count the spider/Pinion gears, 4 +2 side axle gears = heavy duty sought after diff. Which came standard with 3:36 and numerically higher gears. In good shape they should fetch between 12 to 1500 dollars. Either way if you have a 3.36 that is a great all around ratio when not using an overdrive Transmission.