In general I have seen manual transimissions last alot longer than autos when they are pulling a big load. I don't know about the new Dodge autos, but IMO a manual is stronger than a auto.

 

You should take a look at the "mega cab" dual. It has a completely differant bed with even cooler fender flares... at least imo.

 

in stock form the manual maybe a better way to go but if you want more power, the auto would be a better choice. There are alot of things you can do to an auto to help it hold up to 1200 ft lbs of tq and tons of HP. Basiclly you can make the AT nearly bullet proof.