From The Album "Drumming / Music For Mallet Instruments, Voices And Organ / Six Pianos " [1974] info: http://www.discogs.com/Steve-Reich-Drumming-Music-For-Mallet-Instruments-Voices-And-Organ-Six-Pianos/release/249712 Glockenspiel – Ben Harms, Glen Velez Marimba – Bob Becker, Russ Hartenberger, Steve Reich, Tim Ferchen Organ [Electric] – Steve Chambers Percussion [Metallophone] – James Preiss Voice – Janice Jarrett, Joan LaBarbara Voice [Melodic Patterns With Marimbas] – Jay Clayton