Huh, something is off. I've done it a bunch as well. What I do is put a chalk mark on the tire at 12 o'clock, then a chalk mark on the pinion flange. Then turn the wheel one revolution and watch the chalk mark on the pinion, count revolutions on pinion. Trans in neutral of course. The count of revolutions should be close to one of the below #s. Most common ratios are 2:73, 3:08, 3:27, 3:55, 3:73, 4:10. Assuming you have a 8.8 GT rear.