This is a really neat little bit of music. The show was billed as Mickey and the Heartbeats (or, possibly, Jerry Garcia and Friends), and Bobby and Pigpen (and probably Billy) were both absent. Jack Casady and Spencer Dryden sat in on the first set, and Casady and David Getz sat in on the second. There is also supposedly a third set that is in circulation, and Harvey Mandel and George Chambers sat in on that one. The entire show also possibly a composite of shows from the 23rd and 24th of December, 1968.