I think you have a good fright with the dealer myself.There so dealers out there that give's you time to bring it back if your not happy with the vehicle,It sure wouldn't hurt anything to go and talk to them about it, and let them know that your not happy all. You need to checkand make sure that the truck wasn't wrecked in the past and that there trying to pull a go one over you.
You can take it back. It looks as if this truck has been damaged and the box repainted. I cannot guarantee that they will give you a credit for the truck. They will most likely just offer to repaint it.