I just bought a new RAM 3500 DRW. In all of my many years I have been thought that you break in a truck very carefully.
Well, I must be wrong and time to learn something. I don't have the owner's manual in front of me at this time, but in so many words, it's says to run the diesel hard under FULL LOAD (by pulling a trailer) to break in the engine. It states that this will smooth and seat the bearings properly and properly break the engine in during the first 6000 miles to enhance the fuel mileage.
I know, I know,.........I am only the messenger here. I was surprised when I read the diesel supplement to the owner's manual. Not the way I was raised or thought. Times and things are always changing.
Edit: FYI, my 2004 RAM diesel said to NOT tow anything for the first 500 miles.