This episode's headline: Drugs and Sports. The guests include PETER GENT, Author/Former NFL Player; ED GARVEY, Former Executive Director, NFL Players' Association; In Chicago: JIM FINKS, General Manager, Chicago Bears; CARL ELLER, Former NFL Player. Byline: In New York: ROBERT MacNEIL, Executive Editor; In Washington: JIM LEHRER, Associate Editor; MICHAEL JOSELOFF, Producer; GORDON EARLE, Reporter