Something moved when the truck set down on the ground. Wheel bearing can do that. Spindle and back plate should move as one piece, wheel and drum should move as one piece. That only leaves the wheel bearing as a question. but, the wheel cylinder is bolted to the backing plate. The backing plate is bolted to the spindle, and, the brake shoes pivot on the pivot that is bolted to the back plate. Look for any movement at those places as well. A last thought, spindle to drum, any movement here will be an issue as well.
