2500HD 4X4 4-door with 6.0 My dad has the same with Duramax. I like the gas better, especially for off-road. It is around $5,000 more for the diesel and if you take what is costs to finance $5,000 then take what it costs more for the fuel mileage difference of the gas, the gas is cheaper. I doubt you will run enough diesel through it to pay for that $5,000 more. Also, if I only go about 60 or so, I can easily get 15 or 16 mpg. Once I get over 60 though, which is most of the time obviously, I average about 14.5. Other than fuel mileage, you cant beat the HD though.