Any way to tell the gear in a rear off the car
 

So I'm going to pick up a 10-bolt rear tomorrow that according to the seller has 4.11 gears in it (strange I would have expected 4.10s in a 10-bolt). What I want to know is:

What ratio is it between the spinning of the axle hub/wheels compared it to the pinion yoke? Will it actually be 4.11 rotations of the pionon to get one complete rotation of the wheel?

or

Is there any other way of telling what gears are in the rear without opening up the dif?

Thanks and sorry if that's a bit of a newbie question, I'm really not smart on gears.

Yes, yes, and no.

Best way is to take a 1/2 socket and rachet, pop the cover and count the gears. Usually the aftermarket gears will have the # of teeth stamped on them.

If you don't want to open the cover, yes, the drive shaft will turn 4.11 times for each wheel revolution.

Easy to tell the difference between 3.73 and 4.11, but not between 4.10 and 4.11.

Good advice. Slightly more then 4 full rotations of the pinion = 4.10s. Three and 3/4s turn = 3.73s. About 3 and a half turns is 3.42s and so on.

Awesome! I'm fine if it's 4.10s or 4.11s, just want to make sure it's not 3.42s and just being told it's 4.11s. No what I mean?

Thanks y'all, I'll count the rotations of the drive shaft.