Of course, we all know and love the Grateful Dead once-only special guests The Beach Boys on April 27, 1971 at the Fillmore East closing week, but what I didn't know until now (or remember) is that the Jerry Garcia pedal steel version of the New Riders of the Purple Sage
They also played at Day In The Green #1 on June 8, 1974, but no such riot there. In the background is 4-25 and 4-28 Fun Fun Fun's sandwiching the 4-27 Riot
The awesome JGMF discuss New Riders first playing Beach Boys here
You are starting with my favorite track from that April 27 pairing "Riot In Cell Block #9" but stay for both versions of Fun Fun Fun at the back end of the tape.