Rear Axle or Gear Confusion

It’s probably a 9 1/4 rear. Dodge had a shim kit to put on the spiders that go on each end of the pin in an open diff. I can’t remember if u replaced them with thicker ones or they were missing and u had to add them. But like said it’s probably normal wear for the mikes it has. I have seen the axle splines worn. Kim