Do a search on the web and look for new hitches by the manufacturer, enter a hitch for your year of XJ, then a hitch for the year ZJ/WJ that has the potential hitch. I'm betting they won't work. I remember someone asking me if the hitch I had for sale would fit a '93 grand and I did that same interweb search and the mounts were vastly different. I have a feeling it's totally dependant on the bumper the hitch is supposed to fit under - the Grand being lower than an XJ.....
Aren't the Grand Cherokee gas tanks quite a bit lower and quite a bit different in size? I'd think that a G.C. gas skid wouldn't work at all and if it did, it'd hang way down...... :dunno: