[4]The album's opening song, "Thunderbird", despite having ZZ Top writing credit, was originally written and performed by The Nightcaps, a band formed in the 1950s when its members were teenagers.

[7] The song "Heard It on the X" was written about the influence of a Mexican border blaster radio station, X-Rock 80.

[citation needed] In the late 1980s the album was released on CD with the studio recordings being digitally remixed and the original 1975 mix version was discontinued.

The remix version created controversy among fans because it significantly changed the sound of the instruments, especially the drums.

All tracks are written by Billy Gibbons, Dusty Hill, and Frank Beard except where noted^ Shipments figures based on certification alone.