The 2013 RAM will have a DEF tank, the current ones do not. Is this good?? I don't know, but the
www.cumminsforum.com are saying this is good and that the RAM will get better mileage.
My non High Output 6.7 with 3.73 rear pulls my 14K trailer without a problem. The new HO 6.7 have a different transmission in them to support the 800 foot pounds of torque, mine only has 650, but does the job just fine.
Here Is a link to the RAM site, you can look at the towing capacity, but of the 2012's, 13's are not out yet.
http://www.ramtrucks.com/en/towing_guide/?section=heavy