DRIVER WEIGHED AT THE SCALES FOR DELIVERY AND WAS OVERWEIGHT. DRIVER PULLED OFF TO OUR DUMP OFF BIN TO DUMP SOME MATERIAL BEFORE BEING WEIGHED AGAIN. WHILE CLIMBING DOWN TO UNLOCK TAILGATE, DRIVER SLIPPED ON STEPS AND TRIED TO CATCH SELF ON THE MUFFLER COVER. THE SHARP EDGES ON THE MUFFLER COVER CUT RIGHT RING AND MIDDLE FINGERS.