Who was the third Dolphins back?

Today’s question: The Miami Dolphins had a perfect season record in the 1970s. In that particular season, they had two running backs who rushed for 1,000 yards. Who was their third running back who also rushed for over 500 yards in that season?

Yesterday’s answer: Rocky Marciano and Muhammad Ali were a combined 105-5. Rocky Marciano was undefeated when he retired on April 27, 1956. He had a record of 49-0. Ali retired with a record of 56-5. Neither fighter ever fought to a draw.