Regarding diesels in half tons:
On one hand I think the idea is awesome. On the other, I can't figure out why someone would want a diesel half ton. I know, I know, torque and mpgs. The gas power plants currently offered in the half ton markets can already far exceed the design capacity of the vehicle, the temptation to not overload the half ton platform "just because I can" must be overwhelming. I think that is the main reason Dodge is putting a smaller diesel in their half tons vs the larger one in the Titan. Even the point about MPGs is somewhat moot. Local markets vary, but diesel is currently 60 cents more per gallon than 87 at the gas station I drive by every morning. That's almost a 20% difference. If the truck gets 25% better mpg (which may or may not be optimistic), you're looking at saving a whole 5% per mile. 20mpg in a gasser (at 3.45) is 17 cents per mile, 25 mpg in a diesel (at 3.99) is 16 cents per mile. A difference of one whole penny. What will this engine option cost? 5-7k? Your break even point in fuel savings will fall somewhere between 50,000 to 70,000 miles, but that doesn't factor the more expensive oil changes (even DIY) and repair bills.
All in all, I just can't wrap my head around a diesel half ton. Either from a practical, or a fiscal sense. If you need a truck to tow with better road manners, you need 3/4 or a 1 ton with a heavier frame, better tranny, axles, suspension, and brakes.
I predict the diesel half ton will sell a butt load at first, then tank.