Junior Seau!
From what I've researched, no one wore number 21 for the San Diego Chargers in 1998.
Ryan Leaf.
George Roberts
RB Glen Bonner.Bonner wore #21 for the Chargers in 1974 and 1975.
Chad Rinehart is number 78 on the San Diego Chargers.
Ryan Matthews
Andrew Gachkar is number 59 on the San Diego Chargers.
Antonio Gates is number 85 on the San Diego Chargers.
Brad Sorensen is number 4 on the San Diego Chargers.
Brandon Taylor is number 28 on the San Diego Chargers.
Bront Bird is number 97 on the San Diego Chargers.
Byron Jerideau is number 68 on the San Diego Chargers.