the yr and ratio are stamped into the edge of the ring gear on 8 3/4
if its out just turn it to see the stampings
if its in the car jack up one side and turn the tire..if it turns its a pegleg
if you cant turn it its a sg that is holding
if its a sg and after checking one side off the ground,then jack up the other side to check it to see if it holds
should not be able to slip it by hand with tire on
I have seen one side weak cause a smaller tire ran on one side for a while
i have seen sg worn so bad that you can turn it by hand like an open diff
if its out of the housing stick both axle in it and see if you can slip it by hand to check if its holding