I have the car on jack stands. I remember somone saying that you could tell what gear ratio you had by spinning the drive shaft by hand and see how many times it need to be turned to spin the tire once. Well the cars in the air and it takes 1 and a 1/3 turns to spin the tire once. Anyone got any ideas how to find out what ratio I have from this data.

 

One back wheel has to be on the ground or blocked so it doesn't turn or both wheels need to turn in the same direction, the same amount of turns.

You need to rotate the wheel once and count how many times the driveshaft rotates.

Depending on if you have a 10 bolt or a 9 bolt, it looks like you may have something in the mid to upper 2.xx range.