The Lions have signed veteran running backs Mike Bell and Jerome Harrison to shore up their backfield. Ten months after being traded for each other, Bell and Harrison were signed to play together on Monday night. Detroit made the move a few hours after promising rookie Mikel Leshoure tore his left Achilles tendon, ending his season before it began. "We needed some running backs with Leshoure's injury and Maurice Morris still not cleared for contact with his (broken) hand," Lions coach Jim Schwartz said. "Now we've been able to bring in two quality players with NFL experience."