Cliff Williams

We're rockin' around the Christmas tree and into a long list of rock stars who are celebrating their birthdays this month.

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

The news follows Dee Snider saying AC/DC had finished a new album, which would be their first since 2014.

Whatever the band was doing in the city last year, it appears the retired bassist was there for at least part of it.

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.