Oh brother! An '03! This is difficult. I would be concerned especially about the rings and the cylinder walls being scuffed. Even a little damage now would show up later in loss of compression (hard starting, less power, poorer mileage) and loss of oil ring seal (burns more oil, blue exhaust smoke).
But I am fairly new to diesels, does anyone know if they can withstand loss of lubrication better than gasoline engines? Do they have lower combustion chamber temps? Does diesel help to lubricate unlike gasoline??
Problem is, when someone is negligent with the work they perform, there must be palpable, quantifiable damage done in order to get restitution.
In your case, you would probably have to have the engine torn apart to be checked to see if there is any scuffing of the rings/walls/bearings/cams, etc. If there isn't, I don't think the dealer is liable. Even if there is, it still might not help, because the engine is still running & working and so they could say there is no real damage. The damage may not show up for many thousands of miles and then it would be hard to prove that it traced back to this.