Exterior Light Set for the 97-01 XJ
1WL-XJF Turn Signal Set (Cree, XB-D Chips)
1WL-XJE Brake Light Set (Cree, XB-D Chips)
1WL-XJD Backup Light Set (Cree, XB-D Chips)
These lights are expensive, but by far the most reliable I've found. I don't like the price and personally, probably wouldn't buy the brake lights or turn signals because I'm somewhat cheap. However, I gave myself a tester discount and have been running them trouble free for over three years. If you want the best bang-for-your-buck the backup lights are an amazing upgrade. I highly recommend them!
DOES NOT INCLUDE RELAY for turn signals.
Look for an EP27 Novita brand relay at local or online parts stores. Test the relay with stock lights before installing LEDs. It will help with troubleshooting if there are any problems with the install.
See the turn signal set page before ordering. These lights are not compatible with 7-pin trailer lights or any type of trailer brake controller. If you happen to be very highly competent and the patience necessary to solve this in a professional manner, please contact me. I presume some combination of resistance, diodes, and/or rewiring could solve the issue.
One work around is to remove the trailer lighting harness - it plugs into wiring behind the spare-tire-holder panel in the cargo area. If you want to maintain the ability to pull a trailer, these LEDs are compatible with four-pin style harnesses.
Otherwise, I don't think many of us are using an XJ for heavy-duty trailer pulling. There are any number of better options for that sort of work!