We've got an 06 bought new and love it. 125K on the clock now. I do all the work on it except a few warranty issues early on. I did most of the preventive fixes from this forum.
It has the best stock TC (late 06) and we've had no issues. I tried to get dealer to do Euro TC but they wouldn't, didn't qualify. (F37 did get done). It tows light occasionally.
I've done:
EHM at about 15K now Provent since 115K
ORM at 15K then GDE later
External fuel pump then Cummins in tank pump with Stanadyne FM 100 with 2 micron
(Used the Libby canister in the truck)Bright box for headlights
Timing belt, water pump, thermostat, coolant, brake and PS fluid changed at 100K
10K OCI with Rotella and excellent UOA
ALL maintenance done on schedule except missed one trans oil change interval and all done by me except very first oil change at 3K.
Problems:
FVC would get stuck when new due to stock ccv and egr - warrantied, then EHM and ORM - no re-occurrences
BJs warrantied
Window motor replaced
Shocks and springs are shot - might do OME
4X4 shift sensor replaced
Battery crapped out about year and a half ago
Rear brake caliper froze and replaced under warranty (they wouldn't replace the toasted rotor though -

)
To date no other issues. As you can see, almost no drive train problems but has been running clean (egr/ccv) and with good fuel supply nearly all it's life. Runs great, 30 hwy MPG. Wife drives it everywhere and she drives very conservatively. No bio fuel.
If it has a major problem before 200K I'd be disappointed. I'd like to let my wife drive it til about 150K then I plan on a Cherokee diesel or the like for her. Then I'll take over the Libby for a run about until it pukes for good. If anything major happens to it from now on, I don't plan on spending a ton of money on it. But at this point, we are very happy with the vehicle.