Original: Thayil later contributed guitar tracks to Steve Fisk's 2001 album, 999 Levels of Undo, as well as Dave Grohl's 2004 side-project album, Probot.
Simplified: Thayil later contributed guitar tracks to Steve Fisk's 2001 album 999 Levels of Undo, as well as Dave Grohl's side-project album Probot, released in 2004.