Here's a way you can check and closely approximate what your rear gear ratio is. It might be easier to check if you have a friend help:
On a flat surface, block the front wheels and jack up the rear so the tires are off the ground and sit on jack stands. Make sure the parking brake is off and the transmission is neutal. Make a chalk mark on the tire at 12 o'clock. Also make a chalk mark on the drive shaft. Rotate the tire one full revolution and watch the driveshaft as it also rotates. Count the number of revolutions the driveshaft made. This numbe is an approximation of your gear ratio (i.e.: wheel rotated once, drive shaft just slightly more the 4 turns equals close to 4.10 or 4.11 ratio, slightly less than 4 turns probably 3.73). A higher number will give you quicker acceleration and a lower top speed(also less gas mileage.) A lower number means slower acceleration with a higher top speed and better gas mileage.
Like you, I would want to know. This should get you close without having to pull the diff cover again.
