I originally wanted to get a large gas powered (example 2012 Ford 250 6.2L V8 385hp/405tq) but as much power & torque that it puts out, a Ford 250 6.7L Diesel has 400hp/800tq. Doesn't have to be Ford, just noting the large torque difference that'll help get over mountains and through sand etc. So, I guess I'm looking to buy a 4x4 Diesel crewcab truck to pull a large 5th wheel toy hauler that'll be max'd out in weight (XP & 2 quads). I'm not sure if I'll buy new or used by a couple of years so someone else can pay for the depreciation. I've never owned or even been around diesels before so I have no clue really. What is the best out there for dependability, comfort, performance & what is considered 'high mileage' for a used diesel truck?