That "rumble in the rockies" deal was maybe skewed. Claims of a tuned Dmax, subsequent test with 2 trucks off the lot was different, fyi.
Dawg, look up "sulastic" to cure your rough rear ride on the dmax. They work excellent.
As for 6.7, we have 2. One 2011 with 122k needs hpfp, other one is 2013 only has 40k. So far so good.
As for Dmax broken cranks, I have never seen one. One company I service uses exclusively Dmax trucks and tows over 30k regularly. Every truck is tuned and not one failure of any sort since 2001 except lb7 sticks and one vane position sensor.
I have a 2005 lly with 260k and 200 hp over stock tunes with a Suncoast trans. Never touched really and beat the he77 out of it daily. Towed thru rockies and scaled 29,040 lbs. Never took tuner off level 5 and never obeying speed limit. ATS3000 turbo kit. Bone stock motor.