This is the Linda Ronstadt: Box set CD.
Gib Guilbeau plays fiddle and sings background on the previously unreleased song (recorded March 1973):
Lightning bar blues (Hoyt Axton)
Musicians on that song:
John Boylan: producer
Linda Ronstadt: vocals, fiddle
Gib Guilbeau: fiddle, background vocals
Mickey McGee: drums
Michael Bowden: bass
Ed Black: steel guitar
Richard Bowden: electric guitar
Herb Pedersen: background vocals