what gear ratio do i have ????

do a search for that vehicle or the vin # some info will come up , you can always get it in the air put a chalk mark on the drive shaft spin the rear wheels and count the revolutions ,

Beatupchevy is correct. A search for a detailed description of your Jeep will include the axle ratio. I have a 1999 Jeep Grand Cherokee too and I happen to know the axle ratio is 3.55 and I don't think they offered an optional ratio. There is no tag on the differential. Also, the Laredos all had a standard diff, while some Limited models and all Overland models had a limited slip diff called Quadra-Drive. So this 3.55 axle ratio combined with overdrive you will see 1500 rpm's at 55 mph, and 2000 rpm's at 70 mph. That's a relatively slow engine speed which probably explains why they last forever with basic oil changes. On similar note, my Dad and I rebuilt a 1948 Willys Jeep in 1967 and the diff tag said "43/8 ratio" which divides out to 5.375 axle ratio. That's the lowest I've ever seen. So 40 mph was 4000 rpm's. And yes, it was screaming! The Jeep is gone but Dad just turned 100 last month.

01 Grand Cherokee gear ratio