In the '90s, it was a show you had to watch.  And a new book by former NBC President Warren Littlefield called 'Top of the Rock: Inside the Rise and Fall of Must See TV' reveals some new details about TV's best 'Friends'.

Niel Patrick Harris as Chandler? Courtney Cox as Rachel? These are just two of many, never before revealed facts about one of the '90s most popular shows.

Originally called 'Six Of One', the producers later changed it to 'Friends,' which NBC hated.

Six of One was the name of the show during the pilot,” Karey Burke, former prime-time executive at NBC, explains. “Then Kauffman and Crane came back with Friends, which we thought was such a snore. Some people thought the show was too Gen X, way too narrow.”

Turned out to be good decision after all!