Dave Nay posted this a while back... It was pretty good, so I kept a copy of it....
Ivan
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1997’s up - Why better?
The 1997+ XJ has one problem: the t-case output shaft is susceptible to vibes more than the old style case. Who cares? You have to do a SYE anyway to have a "rock eater". The resulting modified case is identical. The aftermarket parts for the 1997+ are virtually the same with the exception of bumpers. And in bumpers, the 1997+ have an advantage.
The newer style XJ has bumper moldings that make up the lower portion of the front flare. When you change the bumper, you lose those moldings and get a flare with the equivalent of major flare trimming on a pre '97. There is simply far less metal to cut. Just put a pre-97 front bumper on a 97+ XJ and you have what they have without all the metal cutting. Nice.
Now, onto the major advantages. In 1997 Chrysler installed a hugely simplified electrical system, fixing one of the major flaws of early XJ's. The '97+ XJ has the Dana 30 with 297-x (D44 size) u-joints. You can (and should) get the 29 spline Chysler 8.25 rearend, which with a set of custom shafts can be stronger than a stock Dana 44 (still c-clip though). In other words, you could run 35's on this axle. The housing is 3" in diameter, easily exceeding the 2.75" housing of the D44, so housing strength is not an issue (D60 and Ford 9's use a 3" diameter housing). For a pure rock crawler on tires over 35" I am not sure either axle is enough, so this may not matter
The interior of the 1997+ is far nicer, especially the dash. The rear hatch is no longer fiberglass and the latches mount to the interior and don't cause rust problems. Structural rigidity with new body style was reported at 40% greater than the older models, very nice when you are dealing with a unibody. I have beat the crap out of my 97 XJ, and it does not have one rattle. Not one. I've owned a bunch of cars that have never seen anything but smooth streets, and they all rattled. My XJ has taken more than it's share of washboard roads and rock crawling, and it is rattle and squeak free. And it weighs 1000 lbs over stock and runs 33" tires. Am I impressed? Hell yes.
Oh, let's not forget that the newer XJ's don't have cooling problems. Owners of older XJ's are always having huge overheating problems in summer (not sure what year they changed the cooling system). My XJ came with the Up Country suspension group from the factory, which meant a 2-core radiator and aux tranny cooler. I've towed a 5,000 lb trailer up-hill (very, very gradually) from the Mississippi to Colorado in 98° temps with no cooling problems. The same trailer was tugged over the Applachians coming from DC (and then down to the Mississippi ). No cooling issues.
This isn't a slam on older XJ's, after all you are building a trail rig and why beat up a newer rig? But with the stronger D30 setup, the nicer interior, the simplified and more reliable electrical system, the better cooling system, and the easier front end work for large tires...IMHO, there is no choice to be made except for purchase price since you have to fix the stupid New Ventures transfer case output shaft design either way. At this stage, a low mileage 1997 XJ would represent an awesome value for building into a trail rig that will last many years.
