Automatic tranny compatibility

I've got an '89 XJ and have been told that I could use up through a '90 XJ for the same transmission. ANyone know what changed in later years/whether i could use a newer transmission (say from an '01)? Most of the ones i've found in my area have a TON of miles on the '89/'90 and I'm hoping not to have to do this again in the near future.

by the way, symptoms were: transmission slipping, burned smell for ATF fluid, took to aamco for free check up and that's what they came back with. It's a 4.0L, '89, 4x4. Thanks for the help!

if you want to keep your t-case you're stuck with 87-90. if you get the t-case with it, 87-96 works. (in 91 they went to 23 spline t-case) the 97+ will need some electrical modifications to work.