The Song:

The acoustic version of "Gamma Ray" was recorded live with his band, and released on beck.com (along with acoustic takes of the entire Modern Guilt album).

Arranging "Gamma Ray" on acoustic instruments made the song more rhythmic, with the strumming acoustic guitar and percussion beats. Jessica Dobson (I believe) sings the song with Beck, almost as a duet, and she adds some subtle acoustic lead guitar licks in there too.