During the 1980 season, Muncie was traded to the San Diego Chargers, where he again was selected for the Pro Bowl twice, including 1981 when he ran for 1,144 yards and 19 touchdowns, tying the then-NFL season record for rushing touchdowns.
During the 1980 season, Muncie was traded to the San Diego Chargers, where he again was selected for the Pro Bowl twice as a member of their high-scoring Air Coryell offense. He enjoyed his best season in 1981, when he ran for 1,144 yards and 19 touchdowns, tying the then-NFL season record for rushing touchdowns.