Finding the gear ratio of a 98 Grand Cherokee
 

I will be working on one that has rear end noises and thinking about a junkyard rear end,is there anywhere on it that has a sticker that will have the ratio code. I do not want to put one in with a different ratio.

There may be a tag on the differential itself that has gear ratio, or, under the hood somewhere, there should be a sticker that states axle ratio. (assuming it hasn't been changed.....) For the most part, it is also etched into the ring gear, so if you roll it, should be able to find it..... (on aftermarket gears at least.....)