Had my 2.7 CRD for 18 months, been reliable but had niggly faults that have been cheap and easy to fix, after looking on forums most appear to be common problems on diesel and petrol WJs.
1. No heating through blend doors failing (that old chestnut), actually an easy fix.
2. Handbrake, with new shoes and drums wouldn't even hold it on auto-creep facing uphill until I modified the mechanism.
3. Remote central locking (again another mod needed).
4. Check operation of rear wiper.
5. Gas struts on bonnet and rear tailgate.
6. Play in steering ball joints.
7. Steering damper leaks. Took mine off and threw it away for the MOT.
8. Seatbelt mechanisms.
9. Key barrels for ignition and fuel cap are poor quality with lots of play in them.
10. Outer doors seals corrode and bubble up. Dealers £240, eBay £140, could be negotiating point.
Also had the following, could be about to happen but be hard to spot.
1. Door glass drops, another mod done by replacing the weak plastic cable blocks.
2. Central locking/electric windows fail through broken wires at door shuts.
Hope this is helpful, happy hunting!