I think you're really gonna like that suspension kit. Two things though:
-If the RE sway bar disconnects get noisy(clunks, clanks, etc), consider dropping $125 on a set of JKS Quicker Disconnects (or look around for used examples)
-On 1997 and up XJ's it's almost 100% assured that you're going to have to run a CV style rear driveshaft with a Slip yoke eliminator of some sort.
Google hack-n-tap for one style which uses your stock tailshaft. The other is made by several companies including Advanced adapters I think. It replaces the tailshaft with new housing, shaft, yoke, etc. , but requres you take apart you tcase (hack/n/tap keeps it together)
"For He so loved the world, that He sent His only son..."
1992 XJ:"Daddy's Jeep" - The "Please don't hit my Jeep again!" Edition.
2009 Ford Edge:"Penny"- "Mama's new ride, and our new trip car"