Only one member of ZZ Top actually played on their massive hit “Legs”. Billy Gibbons of the band provided the vocal and played guitar on the track. All the other instruments were played by engineer Terry Manning. Personally I find it more amusing that the only member of the band without a beard was the drummer; his name is Frank Beard!
http://www.youtube.com/watch?v=5nZniMYCZp4
With Just A Hint Of Mayhem 