Country musician Johnny Cash also submitted a song to Eon productions titled “Thunderball” but it wasn’t used. The lyrics of Cash’s “Thunderball” describe the film’s story. The producers’ decision to change the film’s theme song so close to the release date meant that only some of the film’s soundtrack had been recorded for release on LP. You can find Cash’s “Thunderball” on the 2011 compilation Bootleg, Vol. 2: From Memphis to Hollywood.
…and here’s what the opening credits would have sounded and looked like, had they used Cash’s song.