I once pulled the diff cover and looked at the number stamped on the ring gear.
Another time I removed the tire and marked the drum and marked the yoke. I slowly rotated the tire a watched how many times the yoke rotated. This gave me a ballpark ratio. Example: 1 complete revolution of the drum,the yoke made approx 2 and 3/4 turns. The ratio of the rear was 2.78 to 1.
I like to turn the wheels 10 times (car off the ground in the back) and count the number of driveshaft turns. Divide the number of driveshaft turns by 10 and you have your gear ratio (~37 turns = 3.73 , ~35 = 3.55 etc)
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