[PetChemMan]

Checking axle ratios can be a bit tricky. For instance, if one rear wheel is on the ground, and the other wheel turning freely, then the free wheel will turn twice as fast as it normally does for each revolution of the driveshaft. That phenomenon is courtesy of the spider gears. Thusly, a 4.0 axle ratio will appear to be a 2.0 ratio. Remember that fact if you are running the car in gear with one wheel off of the ground. If your speedometer reads 60 miles per hour, the free wheel will actually be turning 120 miles per hour ( assuming the speedo runs off the transmission tailshaft.) Also, if both wheels are free to turn, they may both turn in the correct direction, or one wheel may turn backwards, depending on whether the spider gears are turning or stationary. A little more brake drag on one side than the other can mess up your wheel revolution counts, and the difference between a 3.08 and a 3.23 may not be evident.
If you're careful, the following will work for an open, non-posi rear end; jack up only one drive wheel, and mark it at exactly the top or bottom with tape or chalk.
Then carefully mark and turn the driveshaft several revolutions , say 10, and measure the corresponding wheel revolutions. Remember that the wheel would normally only turn half that many revolutions with both wheels turning, so divide the driveshaft revolutions by one half the wheel revolutions to get the true axle ratio. Determining the exact wheel revolutions accurately is still not easy, but the more turns of the driveshaft, the better chance you have of coming up with a reliable number.