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| Name | Year(s) | Appeared on | Instrument |
|---|---|---|---|
| Elliot Ingber | 1966, 1968, 1992, 1996 | Freak Out!, Lumpy Gravy, You Can't Do That on Stage Anymore, Vol. 5, The Lost Episodes | Guitar |
| Barbara Issak | 1979 | Joe's Garage | Vocals |
Read more about this topic: List Of Performers On Frank Zappa Records