calculate rear axle ratio

I thought that also, tryed it , it doesn't work. One turn of the wheel will give you about 1 1/3 revolutions on the drive shaft.

As I said, you evidently have a "open" differential (not a sure grip)

Simply turn the wheel TWO turns and count the shaft.

If you properly counted FULL TURNS (full revolutions) when you turned the wheel 10 times, the shaft should have turned 1/2 of 32.3, or just over 16

Since you seem to have an open rear, you could have turned the ONE wheel TWENTY revs, and the shaft would turn 32.3 turns.