I think the Ram bed setup is fairly new. Try calling the manufactures or visiting their websites to see what they offer. I don't think you can go wrong with any hitch, but some do have better features than others, like 4 axis movement and such. I purchased a Pullrite, because at the time they made the mounting brackets that go under the bed and mount to the frame without welding or drilling any holes in the frame. I do not have the factory prep package that started in 2013 models, so I'd look closely as to who has what.
Checkout this link and you might want to make it one of your favorites for the Dodge Cummins forum. There showing a B&W hitch for your setup.
http://www.cumminsforum.com/forum/20...-question.html