Jack up the jeep in the rear, make a reference mark on the rear tire side wall and down on the concrete. Make another mark on the drive shaft, and the axle housing . Slowly spin the rear tire exactly one revolution , while counting how many times the shaft turns. If the shaft makes just a little over four revolutions then the gear ratio is 4:10 if it makes just a little over three turns it would be 3:07 gears , so on and so fourth. Hope this helps.