all this info below is pertaining to 4.0L models
the cruise control servo is the same from 97-06.. the bracket that bolts it to the driver's side fender is different from 97-02 and 03-06. the vacuum line it uses is the same for all years
jeep cherokee from 99-01 and 99-04 grand cherokees have the same servo.. except the mounting bracket is different...
if you are pre-wired all you'd need would be steering wheel buttons and the servo.
the 03-06 TJ share the same steering wheel/ cruise buttons as a 99-04 Grand Cherokee. I don't know if you can remove/add the buttons on these steering wheels easily as you can the 00-02 models. you might have to replace the entire steering wheel cover/airbag cover.
03-06 mounting style
00-02's servo mounts on a bracket that hold the evaporator canister on the driver's side fender beside the master cyl.
I know why too much about jeep wrangler cruise control