For the last 45 years, ZZ Top has been the most dependable bands in rock and roll, sticking with the same three-man lineup while groups like the Rolling Stones, Black Sabbath and even AC/DC underwent a series of personnel changes. But did you know that in the brief time before the Little Ol’ Band from Texas settled on their current configuration, no less than three other people were in the group? Here are their stories.

As longtime ZZ Top fans know, the band evolved out of Moving Sidewalks, guitarist Billy Gibbons' psychedelic blues-rock band. The group released one LP, 'Flash,' in 1969, but after Sidewalks members Don Summers (bass) and Tom Moore (keyboards) were drafted into the army, Gibbons and drummer Dan Mitchell decided to put together something new rather than replace their missing bandmates and continue on under the Moving Sidewalks banner.

Gibbons and Mitchell aligned themselves with organist Lanier Greig, whose Hammond added swirling texture and a bass line to the newly christened ZZ Top's 1969 debut single, 'Salt Lick'/'Miller's Farm.' But before the year was out, so was Greig, replaced by bassist Billy Ethridge -- and Mitchell was gone too, with new (and current) drummer Frank Beard taking his spot at the kit.

That's an awful lot of turnover for the first year in a band's existence, but the changes to the ZZ Top roll call still weren't finished. After the band was presented with a contract offer from London Records, Ethridge departed; fortunately, Beard was sure the bass player in his previous band the American Blues would make a good fit. One jam session with Dusty Hill later, the ZZ Top we know and love today was born.

"Frank and Dusty had worked together for three or four years before I met them," explained Gibbons in a 1990 interview. "Our initial introduction was brought forth by Billy Ethridge, who was a bass player and keyboardist from Dallas, and he just happened to mention one day that he had a friend coming into town who could really slap the sides off of skins, and he said, 'I think you ought to meet him.' And that led to a jam session that lasted well into the night, and shortly thereafter Frank said, 'I want you to meet a bass player; he's also from Dallas, and I think you'll enjoy it.'"

As Gibbons quickly discovered, Beard was correct. "This followed a great audition afternoon," he recalled. "We played with a number of bassmen, and Dusty picked up the guitar and I think we shuffled for two or three hours in the key of C, and at dinner time we said, "Year, that was nice!" That's basically how all this madness got started."

Gibbons and Mitchell recently reunited for the first Moving Sidewalks gigs in decades. Greig, who migrated to Los Angeles and found success as a session player after exiting the band, passed away in Feb. 2013, at the age of 64.

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