The only real difference between the fenders, besides the flare, is the corner. On '96 down the corner is cut at an angle. With the '97 up it is rounded off. So if you put an older fender on a newer XJ the corner won't "flow" to the front header panel like it's supposed to. If something like this doesn't bother you then those fenders will work on your rig. Which you should be able to figure out since they are pictured on a newer rig, regardless of what the year range listed is.
I've been told that the header panel bolts on in different locations between the old and new. I haven't ever confirmed this, but if it's true, all you have to do is drill new holes for the studs. If you look around on here there are a few people whole have put the newer header panel on an older rig and kept the older fenders