The aftermarket has come around with Ford 6.0 support. There are a few main issues that, if left unaddressed, can lead to the big expensive issues. I used to be on the Ford 6.0 is junk bandwagon, but have recently seen the big issues can be prevented. The problem is, if you're buying a used truck, you really don't know the service history and if the big problems are already starting to creep up.
If you find a 6.0 you like, keep in mind you'll probably want to put about $2k into it off the bat to ensure reliability. The "good" thing about this is, because of the bad rap, it may actually be cost effective to buy a cheaper 6.0 truck and do the repairs.
These are the couple smaller problems I know about so far:
Oil Cooler - The oil cooler uses engine coolant in the heat exchanger. The coolant side of the heat exchanger is known to get clogged with sand. This sand is leftover in the coolant passages after casting the engine block. Plan on a new oil cooler, flushing the cooling system, and adding an aftermarket coolant filter to catch whatever doesn't get flushed. A blocked oil cooler usually leads to high oil temps causing bad injectors.
EGR/EGR Cooler - the cooler is known for developing small cracks. The EGR cooler also gets plugged with sand from the coolant. These can lead to losing coolant over time and/or overheating. Plan on replacing the EGR cooler with an aftermarket unit or a delete kit and tuner.
FICM - Fuel Injection Control Module. I don't know a lot about this issue but have seen some people complain about problems with rough idle and cold starts, and it's blamed on low voltage from the FICM to the injectors.
The big issue:
Head gaskets - The big issue which gives these engines bad raps is losing the head gaskets. It sounds like running the engine hot due to combinations of the above problems can ruin the head gaskets in a hurry. A lot of people say the factory head studs can be stressed by these heat issues. If you really want to nip this thing in the bud, and you feel it's worth investing more than $2-3k into making a truck fully reliable, plan on pulling the heads and installing new head gaskets and an ARP stud kit.
Lots of good info in this thread, and tons more if you do some searching on the net.
http://www.pirate4x4.com/forum/tow-r...-reliable.html