C pentatonic minor for the first lead break (Grateful Dead first album), and then C pentatonic major for the second lead break.
Blisteringly fast, Jerry is. They said they were all on speed that day, and it shows.
The lead breaks just go crazy, and are virtually impossible to learn as played by them. You can get close, but life is hell trying to get too close.
From slowing things down on my JamMan, and slowing that snippet down, and doing it yet again one more time, the note sequences are truly strange, and not obvious.
Why Jer did it that way, I don't know. But he does connect the notes coherently, but I bet he could never duplicate his feat from those takes.
I also get the feeling the lead breaks are edited from a bunch of takes. The stuff is just too incoherent.
Gotta love those bass notes that define the song. Just wish I could get an innate feel for the lead breaks, for what he was trying to capture, other than just blister fast picking.