If you buy a modern diesel with an auto behind it and plan on towing huge loads or making some real power expect to drop some real coin in the transmission department, it doesnt matter if its a ford, dodge, or chev. The chev rides the nicest and has the nicest interior but has fail independent front suspension. The ford and dodge have real front axles, the cummins is better than the powerstroke, the ford has a better trans and interior than the dodge. 6L are ok motors as HR said but the challenge is finding one that hasn't already been boot fucked. I'm partial to the dodges, imo the cummins is the best motor for pulling and the cheapest/most reliable to make big power with. If you have a bunch of money get the 6.4 ford, delete the egr and dpf, slap on a spartan tune and make 600+whp. Just be sure to sell it before the warranty is up.