Seems as though this discussion continually surfaces....
As 5-90 said you WILL need to upgrade you battery cables and the charging cable from the alternator to the PCM in the engine compartment.
When I did the uprade I built my own cables from 2 ga fine stranded polarity colored pos and neg cables with fusion battery clamps and terminals. The ground pigtail and the alternator charging lead were 4 ga fine stranded with fusion terminals.
When I upgraded the charging cable I remove the small fusible link and installed a 150A marine grade mini buss fuse and fabricated another terminal for the PCM.
Used a 136A alternator from a 98 ZJ 5.2L 4x4 which required that I grind the aluminum mounting bracket as shown previously and also the black stamped steel front mount to clear the larger alternator case.
You will need to remove the original charging cable terminal boot and install it on the new alternator since there is a pin that positions the boot properly. Good idea to swap the serpentine pulley since the XJ and ZJ pulleys are different diameters and extra grooves.
This modification has worked very well with upgraded headlights, off road lights, ham radios, and several other items...