Guessing the Diff. Ratio

[James Densley <jamesd@wsunix.wsu.edu>]

I am wondering if it is possible to figure out the differential ratio, or
number of teeth on the ring gear without taking off the cover and just
counting.  Can you jack up one rear wheel, put it in neutral and turn the
wheel and see how many times the drive shaft rotates for each wheel
rotation?  Or do the planetary gears come into play?  I would think that
if it was done on the r.h.s. it could be possible.  

Jim