Released in 2006, Imaginary Diseases compiles for the first time all live recordings from a very rare and undocumented Zappa band line-up. In 1972, after taking a 20-piece 'electric orchestra' on the road for 8 dates as The Grand Wazoo, FZ reduced the personnel to 10 pieces and toured this new band for roughly 2 months. Billed as The Mothers Of Invention but eventually becoming known as the 'Petit Wazoo,' audio from this period was never released during Frank's lifetime.