Background: Skyhooks were an Australian rock band formed in Melbourne in March 1973 by mainstays Greg Macainsh on bass guitar and backing vocals, and Imants "Freddie" Strauks on drums. They were soon joined by Bob "Bongo" Starkie on guitar and backing vocals, and Red Symons on guitar, vocals and keyboards; Graeme "Shirley" Strachan became lead vocalist in March 1974. Described as a glam rock band, because of flamboyant costumes and make-up, Skyhooks addressed teenage issues including buying drugs "Carlton (Lygon Street Limbo)", suburban sex "Balwyn Calling", the gay scene "Toorak Cowboy" and loss of girlfriends "Somewhere in Sydney" by namechecking Australian locales.
Context: For Skyhooks, the replacement of Hill by Strachan was a pivotal moment, as Strachan had remarkable vocal skills, and a magnetic stage and screen presence. Alongside Macainsh's lyrics, another facet of the group was the twin-guitar sound of Starkie and Symons. Adopting elements of glam rock in their presentation, and lyrics that presented frank depictions of the social life of young Australia in the 1970s, the band shocked conservative middle Australia with their outrageous (for the time) costumes, make-up, lyrics, and on-stage activities. A 1.2 metre (4 ft) high mushroom-shaped phallus was confiscated by Adelaide police after a performance. Six of the ten tracks on their debut album, Living in the 70's, were banned by the Federation of Australian Commercial Broadcasters for their sex and drug references, "Toorak Cowboy", "Whatever Happened to the Revolution?", "You Just Like Me Cos I'm Good in Bed", "Hey What's the Matter", "Motorcycle Bitch" and "Smut". Much of the group's success derived from its distinctive repertoire, mostly penned by bass guitarist Macainsh, with an occasional additional song from Symons--who wrote "Smut" and performed its lead vocals. Although Skyhooks were not the first Australian rock band to write songs in a local setting--rather than ditties about love or songs about New York or other foreign lands--they were the first to become commercially successful doing so. Skyhooks songs addressed teenage issues including buying drugs ("Carlton (Lygon Street Limbo)"), suburban sex ("Balwyn Calling"), the gay scene ("Toorak Cowboy") and loss of girlfriends ("Somewhere in Sydney") by namechecking Australian locales. Radio personality, Billy Pinnell described the importance of their lyrics in tackling Australia's cultural cringe:  [Macainsh] broke down all the barriers [...] opening the door for Australian rock 'n' roll songwriters to write about local places and events. He legitimised Australian songwriting and it meant that Australians became themselves.  The first Skyhooks single, "Living in the 70's", was released in August, ahead of the album, and peaked at #7 on the Australian Kent Music Report Singles Charts. Living in the 70's initially charted only in Melbourne upon its release on 28 October 1974. It went on to spend 16 weeks at the top of the Australian Kent Music Report Albums Charts from February to June 1975. The album was produced by Wilson, and became the best selling Australian album, to that time, with 226,000 copies sold in Australia.  Skyhooks returned to the Sunbury Pop Festival in January 1975. They were declared the best performers by Rolling Stone Australia and The Age reviewers, and Gudinski now took over their management. The second single, "Horror Movie", reached #1 for two weeks in March. The band's success was credited by Gudinski with saving his struggling Mushroom Records and enabled it to develop into the most successful Australian label of its time.  The success of the album was also due to support by a new pop music television show Countdown on national public broadcaster ABC Television, rather than promotion by commercial radio. "Horror Movie" was the first song played on the first colour transmission of Countdown in early 1975. Despite the radio ban, the ABC's newly established 24-hour rock music station Double Jay chose the album's fifth track, the provocatively titled "You Just Like Me Cos I'm Good in Bed", as its first ever broadcast on 19 January.
Question: What happened in the seveties?

Answer:
the replacement of Hill by Strachan was a pivotal moment,