What position did Franco Harris primarily play?

What position did Adrian Peterson primarily play? Adrian Peterson is best known for playing with which NFL team? Which college was Adrian Peterson playing for when he entered the NFL? What jersey number did Adrian Peterson wear with the Vikings? 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? What position did Curtis Martin primarily play?