maybe I'm lucky but my 6.7 has performed well, 13-14 mpg in town, 19 highway, more than enough power to haul any rig parts I've got in the box, anyway 5.9 or 6.7, Cummins every time!
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07.5 quad cab 6.7L 2500, 4X4, mineral grey, 6 speed man., big horn w/ carpet delete, chrome door handles, trim and mirrors, MBRP 4" DPF back muffler delete, spray in bed liner