What position did Curtis Martin primarily play?

What position did Franco Harris primarily play? Franco Harris is best known for playing with which NFL team? Which college was Franco Harris playing for when he entered the NFL? What jersey number did Franco Harris wear with the Steelers? Curtis Martin is best known for playing with which NFL team? Which college was Curtis Martin playing for when he entered the NFL? What jersey number did Curtis Martin wear with the Jets? What position did Terrell Davis primarily play?