Forty years ago last Tuesday, October 11, Frank Zappa & The Mothers of Invention played two landmark marathon gigs at New York City’s renowned Carnegie Hall—a series of performances that, while recorded, have not seen the light of day since. That all changed last week when the Zappa Family Trust announced the release of a massive four-cd set of the performance via Zappa imprint Vaulternative Records.

Recorded in gloriously old school mono, the performances feature Zappa and The Mothers in their weird, stunningly talented prime. Both Carnegie performances will be included in their entirety on the CD set.  Pre-orders began last week and will begin shipping on October 31.

“We tweaked and we tweezed and did everything possible to be certain this does not sound like a breakfast cereal gone mad somewhere in the Van Allen Belt.  I am happy to say The Mud Shark Legend Continues,” said Zappa’s widow Gail Zappa in an accompanying press release.

Zappa was inducted posthumously into the Rock & Roll Hall of Fame in 1995 and garnered a Grammy Lifetime Achievement Award in 1997.  He passed away in 1993.