Gotta go with RCP Phx on this one.
Why are you doing this?
Do realize how many separate harnesses are in a '99 XJ?
Off the top of my head I am going with at least 20.
Just the little door jamb plungers that turn on your interior lights
when you open the doors are separate little harnesses.
As a matter of fact I have been hoarding harnesses.
Picking them up off Ebay and out of the boneyard if the price is right.
Really don't know why though. LOL.