After the near "fiasco" level issues and complaints surrounding the 6.0 Powerstroke, Ford needed to wipe the slate clean and start over. With the 6.4 Powerstroke engine that's exactly what they did.
Equipped with a uniquely designed twin turbo, the 6.4 Powerstroke was powerful. It burned cleaner and the 6.4 diesel engine was quieter. A seeming utopia... That is until emissions regulations got involved.
Owner reports on the 6.4's MPG were abysmal. But despite that black eye, Ford's 6.4 Powerstroke proved to be strong, silent, reliable, and clean-burning (Thanks to it being the first Powerstroke to utilize a Diesel Particulate Filter—DPD)
Yes, from 2008 to 2010 the 6.4 Powerstroke, based on International's MaxxForce 7 engine, was a faithful, albeit "thirsty" beast. But the 6.4 was not without its ... problems.
6.4 Powerstroke problems included: leaking radiators, similar to 6.0 EGR cooler and valve issues, restricted exhaust system thanks to the DPF, and bolts holding the twin turbos together simply FALLING OUT (Wait, what?).
But despite those issues the 6.4 Powerstroke, well-maintained of course, is an awesome Ford truck!