That's my truck - 2013 RAM 3500 long bed, 4WD, crew cab Laramie, Cummins Turbo Diesel with the Aisin transmission, cherry red in color. Had it about 3 months now.
Like ScottG said - DEF is not a big deal. The truck holds 4 or 5 gallons of DEF. I got around 750 MPG while towing, and it's relatively cheap - less than $3 per gal. I think you can get >1000 MPG of DEF when not towing. They sell DEF at most gas stations in containers, and dispense it at most truck stops.
Fuel mileage - towing = 10.5 to 11.5, typically. I actually got 12.8 once, but that was unusual. Not towing = 18 - 19 MPG interstate, but I haven't measured it but on one long trip.
The Aisin transmission is a "heavier duty" transmission; from what I hear it was made to compete with the Allison transmission.
I Love the exhaust brake on the RAM!