What was far more noteworthy at the time – besides the oppressive heat – was that Dickey Betts, Berry Oakley, and Jaimoe joined the Dead for the final five tunes. Starting with Sugar Magnolia, the band morphed into a Dead-Allmans super group. Dickey Betts emerged first, followed by Berry Oakley and Jaimoe. With Phil reportedly stepping aside, the Dead suddenly found themselves powered by Oakley’s muscular bass, a momentary return of the twin-drum attack, and another smoking guitar.

Sugar Magnolia is hot from the get go and turns downright blistering in the Sunshine Daydream portion. The Not Fade Away that follows has loads of energy and verve all its own. There, Oakley’s bass dominates the mix, pushing the music forward with a thick, percussive drive while Jaimoe and Billy create a relentless rhythmic engine underneath. On top of this Garcia and Betts trade leads rather than challenge one another, with Garcia generally taking the more assertive role and Betts weaving melodic responses around him. The result is less a guitar duel than a conversation between two very different approaches to improvisation. Keith also comes in with some fierce fills. Towards the end, the band eases out of the groove into a surprisingly delicate passage. For a minute or two, the frantic energy gives way to something more patient as Garcia and Betts intertwine lines in a mellow moment that is truly an Allmans-Dead hybrid that continues into Goin’ Down the Road Feeling Bad as Betts adds that wide open spaciousness so characteristic of the Allmans to the Dead’s trusty monster. Drunk on their own power, the band then goes to a wild Hey Bo Diddley. A mad Johnny B. Goode, seemingly without Dickey, caps the evening.

The next night Jerry, Bobby, and Billy returned the favor by sitting in with the Allman Brothers at Gaelic Park. For this brief moment in July 1972, two bands that had independently redefined the possibilities of live improvisational rock and roll actively looked for opportunities to share the stage with each other. And when they did, neither group abandoned its identity, but each bent slightly toward the other. More than half a century later, those performances remain a testament to the respect, curiosity, and musical generosity that existed between the two camps. And it also gives us some incredible shit to listen to.