The gear ratio is base on the number of teeth on the ring gear/the number of teeth on the pinion gear, i.e. 41 ring gear teeth/10 pinion gear teeth = 4.10 gear ratio. With the cover off to check the ratio, also check the gears for a good mesh pattern. Additionally, check the gear oil for any sign of suspended shavings. Also, grab the backing plates and pull them in and out to check for excessive slop. A good deal on a 14-bolt with 4.10 ratio, can be be a bad deal if the rearend requires a new ring and pinion master setup. Good luck with your search and I hope this information is helpful.
