adding a rear hitch

If i add a rear hitch to my jeep to towe , will i need a differant diff.?
and gears.

i didn't get a factory towe package, guess my question is can you towe with a regular diff and gears.?

What tranny do you have, and what year XJ?

Once Chrysler took over, they didn't use different gears for the tow package. The automatics got 3.55 gears and were rated to tow 5,000 pounds. The 5-speeds got 3.07 gears and were rated to tow 2,000 pounds -- primarily because Chrysler didn't want to pay for burned out clutches. The tow package included a heavy-duty radiator and, for the automatic, an external tranny cooler.

That's about it.

oh i see, so it's just a differant radiator and cooler.

I have 3.55 gears in rear.
have Aw4
is a 2001 sport.

Depending on the tongue weight of your trailer, you might also want to look at some helper springs in the rear.