i have been doing much research on the same thing, here is what i found:
to get it "back to stock" really depends on which stock ratio you have. there are 3.27 (most sports), 3.55 (most 4-drs), and 3.73 (optional)
you more than likely have 3.27 gears like me. to find out for sure, there is a tag on the #2 bolt on the rear diff or you can look at the sticker inside the drivers door and cross-ref. it on this site.
if you have 3.27s and go to 33x12.5 tires, 4.10 would probably get you closest. if you were running 3.55 or 3.73, i would say 4.56 or maybe 4.88 if you feel ambitious. it has also come to my attention that most gears in 3.27.3.55.3.73.and 4.10 for the ex run the same price but they get higher after that. it has also come to my attention that above 4.10 you will need to notch a cros pin or buy one tat has already had this done which will be another 30 bucks.
a word to the wise, if you dont have limited slip in back, i would buy one and have it put in when you do the gears (about another 360+, depending onthe unit).
also note that on 4wd vehicles when you regear the rear, you must regear the front. if you have gearing any different that .01, you will have binding and probably break something, so start looking at gears for that dana 35 up there.
my plans for my sport (once i get the other half or my lift and 33s) include 4.10 gears and a detroit soft locker in the rear (basically a posi). this would probbaly be a good idea for you too.
