TELEVISION - May 28, 1992

Air Dates: Ed McMahon, who toiled alongside Johnny Carson for 30 years, is about to see what life is like on the competition. McMahon will be a guest on Arsenio Hall’s late-night show on Monday (11 p.m., Channel 13). . . . Veteran broadcast journalist Joseph Benti and actress Dyana Ortelli host “Transit 2000,” a new monthly magazine series about transit and the environment produced by the Southern California Rapid Transit District, Sunday at 10 p.m on KCOP Channel 13. . . . Malcolm-Jamal Warner, late of “The Cosby Show” and soon to have his own series on NBC, hosts “The U.S.A. Music Challenge” for ABC. The pop music showcase airs next Thursday at 9 p.m. on Channel 7.