What is the easiest way to figure what axle ratio is in my jeep I have a 1999 Cherokee and I am pretty sure it is stock does the vin tell me or is there no other way than pullin the diff cover and counting teeth  

jack it up and spin the shaft by hand and count tire rotstions. there might be a tag on the diff that tells you  

If no one has messed with the axle, there should be a tag still on it that gives the number of teeth on the pinion, and the number of teeth on the ring.  Just divide the smaller  into the larger, and there's your ratio.  

I got mine by going in to my local Jeep dealer and asking for the options list and they asked for the last 8 of my vin and pulled everything I needed.  My local guys didn't charge me but I don't know if other dealers do or not.  

this might help ya
http://www.automotive.com/1999/12/jeep/cherokee/specifications/index.html