I've got 51,000 miles on it.
I purchased it with 19,000 miles on it less than 2 years ago.
Since then I've had
1. warranty on air conditioning
2. warranty again on air conditioning
3. warranty on power steering pump
4. back to shop the next day because the steering sucked, 1.5 years later and it's still not how it was when I bought the truck-dealer keeps telling me it's because the truck is modified, I've had 9 modified trucks like this and this one steers the worst.
5. turbo failed, sat at dealership for 3 weeks
6. EGR cooler failed, engine heated up, head gaskets replaced-sat at dealership for 4 weeks waiting for authorization from Ford
7. back to dealership again after driving home 6 hours with no A/C because dealer in CA didn't recharge after head gasket repair
8. Injectors failed-Ford claims they were not torqued down properly from head gasket repari, Dealer claimed they did repair properly. Ford picked up the warranty
9. A/C still not nearly as cold as it should be, I'm just dealing with it.
With that said, there is no vehicle I would rather drive than a Crew Cab powerstroke Superduty lariat. Even with 37s on 22s and 8" of lift I am getting around 14 mpg. I would not get a 6.4 yet because they have really low MPG results and have a ton of issues. I also had an '04 that I purchased with 6,000 miles on it and sold with 28,000 miles on it and that truck had a transmission fail a 11,000 miles and then again at 14,000 miles. Other than that the truck ran flawless. Also a good friend bought an '06 with the same mileage as me, has 4" lift on 35s and has more miles than I do and only has taken his truck to the dealer for a small oil leak under warranty. I guess I just got "lucky" on mine.