George Young, the older brother of AC/DC‘s Malcolm Young and Angus Young, and, along with Harry Vanda the producer of many of the rock band’s albums, died October 22, 2017, at age 70. No cause of death was indicated. Earlier in his career, George Young was a prominent musician, most notably as rhythm guitarist and co-songwriter with Vanda of the Easybeats, who scored a huge worldwide hit in 1966 with “Friday on My Mind.”

On their Facebook page following Young’s passing, AC/DC wrote, “It is with pain in our heart that we have to announce the passing of our beloved brother and mentor George Young. Without his help and guidance there would not have been an AC/DC.

“As a musician, songwriter, producer, advisor and much, much more, you could not ask for a more dedicated and professional man.

“As a brother, you could not ask for a finer brother. For all he did and gave to us throughout his life, we will always remember him with gratitude and hold him close to our hearts.”

Young and Vanda produced AC/DC’s first five albums, beginning with the initial Australian version of High Voltage in 1975 and continuing with T.N.T. (also 1975), Dirty Deeds Done Dirt Cheap (1976), Let There Be Rock (1977) and Powerage (1978).

Young, born in Scotland, first came to prominence as a member of the Easybeats, who scored a big worldwide hit with the 1966 single, “Friday on My Mind.” With Young on rhythm guitar, the Easybeats formed in 1964 in Sydney, Australia, with lead singer Stevie Wright, drummer Gordon Fleet (both from England), and lead guitarist Vanda and bassist Dick Diamonde (both from the Netherlands).

After some early success in Australia, the decision was made to relocate to London, England, in 1966. They recorded the Vanda-Young composition in September and on November, 17, 1966, it was released as a single. The song earned the Easybeats their second #1 in Australia, reached #6 in the U.K. and became their only U.S. hit, though it peaked at just #16 on the Hot 100.

Related: Our feature story on the Easybeats

Simultaneous to their early work with AC/DC, Young and Vanda formed a pop rock band in 1976 with a tongue-in-cheek name, Flash and the Pan.