If you aren't sure what gear you have, jack up the rear and put jack stands under the diff. Put a chalk mark on the driveshaft and on the housing that line up. Put a mark on the bottom of the sidewall on the right rear tire put a corresponding mark on the ground. Slowly turn the right rear tire forward one revolution (mark to mark) while counting the rotations of the driveshaft.
If the driveshaft rotates, let's say, 3 and 1/3 tuns to one complete rotation of the tire then you have 3.23's.