This is my first time on a forum, but I have some questions so please forgive me if I'm not doing this correct. I have purchased 2 f350's one that was bulletproofed, and the other not. Both have 6.0 engines. I have blown the heads on both because I haul a 3-car hauler. Which engine is better, a cummins, durmax, or should I go with a f450. Please give some advice before I waste anymore money