The year makes a difference. Make sure that you get the right year for the steering shaft, because they changed, in 97 I think, and the top end will not interchange. Visually they're easy to check because the later ones have a rubber bellows on the telescoping portion. Older ones require that you remove, or loosen and tilt, the steering box to get the shaft out, because you cannot telescope it without damage. Newer ones will allow the shaft to retract, so you can do it without disturbing the box.
The shaft is keyed so you can only put it on one way. When you do this, make sure, doubly sure, absolutely really effing sure, that you get the thing on the shaft all the way at both ends, so that the clamping bolt actually goes through the crossed keyway in the shaft. That may seem simple enough, but I've seen it done (not on an XJ, though) that someone does not put it on far enough, the bolt goes through beyond the end of the inner shaft, clamping down only on the very end of the shaft, but allowing it to pull apart. Very scary.
Ones I've take off had blue loctite on the bolts, but I see no reference to that in either the 95 or 99 FSM. I also have read that new bolts are recommended, but this also does not show up in either of my factory manuals. It would not be a bad idea, though, if you have any doubt about the condition of the bolts, to replace them, and a little loctite would not hurt.
I've never put in a rebuilt box, so defer to others on brands. If you are looking at a used box from a vehicle you don't know, get a real warrantee, because you may not be able to detect side play in the pitman shaft until it's installed. If your time or travel cost to parts source is valuable, consider that a new/rebuilt may end up being cheaper.
If you go to a parts place, they may have separate numbers for different years. As far as I know, steering boxes are year specific because they changed the boost, making them a little less overboosted in later years. Physical fit did not change, but when I put an 89 box into my 95, I was startled at how soft it was. Whatever year you have, you might consider going with a later box if you don't like that "wheel of fortune" feel.