sentences:  He also worked the American League Championship Series in 1979, 1988 and 1993, and the American League Division Series in 1996 and 1997.Kosc wore uniform number 18 when the American League umpires adopted them in 1980.Kosc and fellow 1976 rookie Al Clark were the first American League umpires who never used the outside chest protector, which had been used since the league's formation in 1901 and was mandated in the 1920s by future Hall of Fame arbiter Tommy Connolly.