Just google 6.4 and 6.7 Powerstroke failures and decide for yourself. You couldn't give me a Powerstroke! The 6.0 resulted in Ford and International in a huge lawsuit, but they are a decent motor if bullet proofed. Tearing them apart is a bit of a pain but if you have some mechanic skills, it can be done. I have done several EGR deletes, rebuilt some High Pressure Oil Pumps, and what not but I am not impressed with a 6.0 at all. Relying on oil pressure to work injectors is not a great design due to cold tempertures making the oil thick. The 6.4 is a disaster in the making from day one. Delete it ASAP if you own it. International decided it would be a great idea to inject fuel in the number 8 cylinder during the exhaust stroke to heat up the exhaust gas to clean the DPF. This would be the regen process. This resulted in literally thousands of engines being destoyed. The truck would need an entire new block. Piston's would sieze/crack and break causing catosrophic failures by bending rods, snapping cranks etc. Get on powerstroke.org, or any other diesel site and search this topic. I would also tell you to get on youtube and search powerstrokehelp.org. Bill is possibly the best powerstroke resource you can find, and he will explain what the 6.4 is all about with a video showing you what he is talking about. Powerstrokes make this guy a living because of their failures. The 6.4 is notorious for having weak rocker arms in the valves. They will fail, just a matter of when not if.
The new 6.7 is ok, but to new for my liking. Someone commented it has twin turbo's and it does not. Ford designed the 6.7 after Internationl and Ford parted ways and came up with a single sequential setup. This has two impellars on a single shaft. It works as a compound system (not a twin turbo system), but the genius engineers decided to use ceramic ball bearings. Turbo's spin very fast and get very hot, cermanic turns to dust at high heat, high rpms, so turbo issues were instant. I do like the reverse flow design that the 6.7 has because it gets exhaust gas to the turbo much faster. They had a lot of high pressure fuel pumps fail as well, and denied warranties claiming water in the fuel. They have since ditched their turbo and fuel pump and outcourced it to people who can build a reliable one. Ford and their warranty is a joke, and they will deny everything. Guys have literally been stuck with 10k plus repair bills because of Ford's inability to put a good diesel in a truck. I seriously urge you to stay with a gas or go with cummins or duramax. After all, both are used in Marine application's which is very demanding on an engine. The powerstroke is not.
I am by know means downing any powerstoke owner, but I see trucks work for a living and I am not impressed at all with a powerstroke.