What about the 6.4L Power Stroke ???

I'm not a fan of the 6.4 PSD and 07.5 -09 6.7 and to lesser degree the non DEF equipped cummins due to the emission issues these trucks suffered from. The Duramax faired off a bit better in their first generation emissions, but even their early DEF version had some teething problems.

I would however highly recommend any 6.7 PSD. My '12 with a 63k miles makes impressive fuel economy, power, and a great 6 speed transmission to back it up.

Good luck...