I'm going to chime in as I've a few experiences with them myself.
I`ve had a 2500 4x4 1998 a while back as my contractor vehicle. It only had 100k km or so, I racked up a good couple of kms on it before I changed it.. It was an amazing truck, very capable and without a doubt the best of the best back then.
I have a 2500 4x4 2003 right now. Just about to hit 300k km. This one is my bike hauler/general stuff carrier/offroade/pop-up trailer tower/hunting-fishing rig.
It's an auto as well. It's an old landscaping company truck and it worked VERY hard. Tranny is still good, you can tell she's getting a tad tired. The company who had it didn't maintain it (I had receipts for stuff but the truck had it's factory oil filter I think, the oil that came out from the tranny and diffs looked like milk chocolate). The truck runs as strong as the day it came out of the factory. It is one hell of a weakling, until you put a module on it. With the EDGE module, it will pull along a g37x that is hugging the left lane and gunning it as you try and over take him from the right at level 3, and on 6, will outright destroy it...Completely changes the truck. I've never been left stranded anywhere with this one, except when both batteries died on me(the day I bought it..). If you maintain them, they are indetructible, and they are VERY fuel efficient. I'm averaging 12.8l/100km right now (downtown ottawa). The first truck had 4.10 diffs, and was the very worst vehicle I had in terms of fuel economy (towing stuff about doesnt help of course), but the 03 with 3.73 is very good on fuel. Always starts without an hiccup unless it'S very very cold, then it takes to tries to get it going The reason I went with them is because the Allison and Duramax combo is absolutely great... only you can't get 10hp more out of them without destroying the allison. It's the best stock truck tranny, and the worse for mods. Being a V engine, everytime you have to bring it in, factor at least 2x as much for a repair than you'd pay for a cummins, and forget working on in yourself unlike you like headaches. I like that the inline 6 is very neat and accesible, everything is within reach. Now, as for the ford well, they make great chassis, don't doubt me, but wow, they haven't made a decent engine in 20 years at least. The 6.0 well, no need to mention anything about it. Afterwards they had the 6.4, which had a shitton of issues such as the flamethrower exhaust, and very large egr valve which requiered a separate water pump which was oversized and caused cavitation in the coolant which enventually failed catastrophically in a typical powerjoke fashion. Also, any service will require the cab being pulled off the frame to access the engine... fuck that shit lol.
Now, with regards to your actual vehicle. The one ENOURMOUS plague of the 6.7 cummins was the emissions shit they added... Lots of people report issues with excessive regeneration and EGR issues. They are better than the 5.9 when all this shit is deleted, and will outlive any engine, but the emission stuff kills fuel economy, the dpf often get blocked, etc. Now, deletes were highly common, but the EPA started cracking down on the manufacturers of dpf delete kits... So they will become rarer.
So this is still hands down the best diesel powered pickup, but lots of the guys are waiting for the 2013 which will do away with dpf and go with def (diesel exhaust fluid), which is being hailed as a revolution for the cummins, bringing back fuel economy and reliability while staying legal emissions wise. So you might wanna consider that. Also, check out cummins foums, so much info there it's not even funny.
Cheers!
