How do I figure out the gear ratio for a Jeep axle that I have?

I have this old Jeep axle, I think its for a 79'. Its a dana 30 and I need to find out the gear ratio for it. How do I found out what it is?How do I figure out the gear ratio for a Jeep axle that I have?
there is a web site that has a calculator, it is so helpfull just enter the number of teeth on the Ring and Pinion gears.








check this web site:


http://www.ringpinion.com/Calc_GR.aspx





How do I figure out the gear ratio for a Jeep axle that I have?
There should be a tag bolted on the cover that has the ratio stamped into it. If the tag is missing you will need to pull the cover. The tooth count is stamped into the side of the ring gear (example 8-28) would be a 3.50:1 ratio. you can also count the # of teeth on the ring and pinion gears, but the pinion gear is hard to see with out pulling the carrier out.
it's probably a 3.54 that's would be stock for most models. I'm not a expert but, I think you must open up the diff. cover and count the teeth. hopefully that helps.
Divide the pinion tooth count into the ring gear tooth count.





I don't think you really need a formula or web site to figure that out.
Pull the inspection plate and count the teeth.