1955: Jack Benny did his last live network radio broadcast after a run of 23 years. He devoted his time fully to TV. 1966: The final episode of "Perry Mason" aired on CBS. 1967: "Mister Rogers' Neighborhood" made its debut. 1967: On "The Tonight Show," Florence Ballard appeared with the Supremes for the last time. 1967: The final "To Tell the Truth" program was seen on CBS-TV. 1984: The final episode of "Hart to Hart" aired. 1987: Roy Orbison performed on "Saturday Night Live." 1988: The reunion movie "The Incredible Hulk Returns" aired. 1992: Johnny Carson hosted NBC's "Tonight Show" for the last time. He had been host for 30 years. He was replaced by Jay Leno. 1997: Fleetwood Mac performed the first of two MTV Unplugged specials that would be aired in the summer of 1997. 2001: The final episode of "3rd Rock from the Sun" aired on NBC.