Diesels get horrible mileage and are much more expensive to maintain, gas trucks get horrible mileage as well but don't cost near as much to maintain. Unless you are pulling heavy equipment, i would stay with the gas. I have a Ram 1500 and pull a 6 x 12 trailer with ztr and stander and average about 10 12 mpg, considering my lead foot it is better than the previous f250 super duty i had. The diesel will pull heavy loads substaintially better, but it will cost you. I have come to realize that good gas mileage and pulling a trailer don't occur in the same sentence.