I know I have kinda asked this question before, but in your guys opinion from what you have drove what did the best on fuel mileage? Also what was it 9 speed, 10 speed, super 10, 13 speed etc... I have heard Detroits do really well on fuel. I'm only hauling containers so I don't need a whole lot of power maybe only 350-400. The most weight I have hauled in my trailer was 44,000. I just was wondering about the variations I have heard cummins is great and bad so just trying to get some ideas here. I have a 89 Peterbilt right now with a 3406b cat engine and it's eating me alive in fuel. Thanks again everyone!