On the XJ (Cherokee) the perches are SOA and a little further apart than the YJ (Wrangler). You will have to move the perches in a little.
Like 4Jeepn said "posi", trac-lock or limited slip differentials aren't much better the open ones. Check into switchable lockers like, Ox Locker, Eaton Elocker or my fav the ARBs.
you're spending that kind of money, don't stop at just the gear ratio.
I caution you have someone with the tools and the knowedge set-up your gears. It's not really complicated, but if it's not done right you'll lose a set of gears and possibly a locker
I took mine to Randy's Ring & Pinion to install 4.56:1 gears and ARB. Damn glad I did.
DO NOT ENGAGE THE FOUR WHEEL DRIVE, UNLESS THE FRONT & REAR HAVE THE SAME GEAR RATIO!!!!!!!!!!!!!!!!!!