On the 04 and 05's there is an issue with the snap ring that holds the axle in place...99% on the drivers side. The retaining clip can break and the axle will never fully snap back into place. Usually this happens when the uca (or leveling kit, etc) are first installed and the insatller will let the stub axle pull out of the diff, its then that the retaining clip breaks. It should just snap back into place, but the clip/internal housing get damaged and never hold the axle properly. This hasn't happened on the 06-08 really at all. And alot of people notice this on the fist very cold moring that they use 4wd on pavement.....the left front axle will pop out of the diff housing. Every single case that has been brought to my attention was dealt with by the dealer replacing the entire front diff housing and assembly. This issue was first brought to my attention back in 05 from a customer in AK, who had an this happen. Turns out that there were a few bone stock Titans/Armadas with the same exact problem. Dealer replaced his diff and no problems since. Again, this seemed to be related to the cold and using 4wd on hard surfaces.
On the flip-side, we have trucks running around out there with about 9" of lift on a Fabtech kit (which is about the most cv angle I recommend) and some of these guys beat thier trucks silly with no ill-effects. We are lucky to have very good CV's on our Titans, but the retaining clips have certainly been an issue.