The chebby has all the service history with it, the guy id be buying it from is the second owner and he bought it from some one he knew personally.the ford on the other hand is on it third owner, and all i know about it is what the current owner knows. Now i have found another truck of possible intrest 08 cummins with twins injectors and a full ats trans with 103k on the clock. Seems interesting but my 05 cummins i had liked to spit injectors so not shure how the new 6.7 is. On the 6.4 problems it seems like you dont have to beat on em to have problems pop up, they can do it with normall maintenance and care.
Edit, the 6.7 cummins is a 07.5 not an 08 and its a full suncoast tranny not ats.85% cp3 100hp injectors twin turbos S480 over 64mm air dog 150 efi live tuning banks intercooler ladder bars.