Background: The Stylistics are a Philadelphia soul group that achieved its greatest chart success in the 1970s. They formed in 1968, consisting of singers Russell Thompkins Jr., Herb Murrell, Airrion Love, James Smith, and James Dunn. All of their US hits were ballads characterized by the falsetto of Russell Thompkins Jr. and the production of Thom Bell. During the early 1970s, the group had twelve consecutive R&B top ten hits, including "Stop, Look, Listen", "
Context: After signing to Avco, the record label approached producer Thom Bell, who had already produced a catalogue of hits for The Delfonics, to work with the group. The Stylistics auditioned for Bell, but he was initially unimpressed. He ultimately agreed to produce the group because he believed in the potential of lead singer, Russell Thompkins, Jr.'s distinctive, nasal high tenor & falsetto voice. Avco gave Bell complete creative control over the Stylistics and he proceeded to focus the group's sound exclusively around Thompkins's voice. On most of the group hits, Bell would have Thompkins sing virtually solo.  The first song recorded with Bell and his collaborator, lyricist Linda Creed, was the lush "Stop, Look, Listen". Bell imported techniques he had perfected with The Delfonics and his musical arrangements worked perfectly with Thompkins' falsetto vocals.  Their hits from this period --distilled from three albums-- included "Betcha by Golly, Wow" (U.S. #3), "I'm Stone in Love with You", "Break Up to Make Up" (U.S. #5), "You Make Me Feel Brand New" featuring Thompkins singing a rare lead vocal duet with Airrion Love, the aforementioned "Stop, Look, Listen", "You Are Everything", and the Top 20 Pop hit "Rockin' Roll Baby" (U.S. #14). "You Make Me Feel Brand New" was the group's biggest U.S. hit, holding at No. 2 for two weeks just as the spring of 1974 turned to summer, and was one of the group's five U.S. gold singles.  The Stylistics' smooth sound also found an easier path on to adult contemporary airwaves than many other soul artists and the group made Billboard magazine's Easy Listening singles chart twelve times from 1971 to 1976, with three entries ("Betcha by Golly, Wow", "You Make Me Feel Brand New", and "You'll Never Get to Heaven (If You Break My Heart)") reaching the Top 10. Every single that Bell produced for the Stylistics was a Top Ten R&B hit, and several--"You Are Everything", "Betcha by Golly Wow!", "I'm Stone in Love with You", "Break Up to Make Up", and "You Make Me Feel Brand New"--were also Top Ten pop chart hits. The group also enjoyed commercial success with big hits with this material throughout Europe.
Question: when did they break up?. Whats the answer?