Originally Posted by dhardison
The easiest way to check the differential gear ratio without pulling the rear cover is to lift the rear end of the vehicle with a jack (using jack stands of course) and physically rotate a rear tire one complete revolution while counting the number of revolutions that the driveshaft/pinion makes. If the drive shaft rotates almost three times, your differential gear ratios would be 2.73:1, etc. Obviously it's not as exact as counting the R&P teeth, but it'll save you pulling the rear cover just for that purpose.
Dan