Actually ZZ Top did have some line-up changes. The original line-up way Billy F. Gibbons, Lanier Greig & Dan Mitchell. Lanier Greig was replaced by Billy Etheridge, who would later bt replaced by Dusty Hill. Dan Mitchell would be replaced by Frank Beard. Now the line-up of Billy, Dusty & Frank are the only ZZ Top line-up to have recorded a full legnth album together as Billy, Lanier & Dan only recorded some singles together.