Darwin
Explorer
"bulletproof" is a buzzword for the gullible, no vehicle is 'bulletproof' even the venerable, and highly reliable Cummins. The "bulletproofing" was done to address the many design flaws with the powerstroke motor. Don't forget when it comes to injectors, with the powerstroke you are buying 8 instead of six as compared The Cummins. The powerstroke also has glowplugs, unlike The Cummins, all the ones I have seen tend to have starting problems in cold weather if all the glowplugs and electrical are not up to spec. I like the milage my old Cummins does when on the interstate, unloaded as high as 21 to 22 mpg. I also like it's track record for a million mile motor. Take your pick, some like the powerstroke and speak highly of them like Drewactual, they also have a larger cab if you have a family (I don't), so something to consider.