SANTA CLARA, Calif. -- The San Francisco 49ers could use some depth on the defensive line.There is a chance they could get some relief in the form of rookies Tank Carradine and Quinton Dial. Both players have been on the Physically Unable to Perform list. They are both eligible to practice next week. Conceivably, both players could be activated by the 49ers next month.However, defensive coordinator Vic Fangio tempered that talk Thursday by saying both youngsters need to be more than healthy to start helping at the NFL level.