Cliff Williams

Three members who left the band at various points during the 'Rock or Bust' tour have returned.

A new social media photo taken around the time of AC/DC's recording sessions last year has fans speculating.

Cliff Williams will play his last concert with AC/DC in Philadelphia on Sept. 20, 2016.

His departure leaves Chris Slade – who had an earlier stint from 1989-94 – as the most veteran member of AC/DC after Angus Young.