So here's a new one for The List: JGMS at Keystone on Tuesday, June 11, 1974.
But note, too, that Merl is playing Sand Dunes on Monday the 10th - this could very easily be a Monday on which Garcia sat in. The fact that Tony Saunders played with Merl and Jerry the week prior (June 4 and June 6) makes it seem even more likely to me. The fact that Jerry played under Merl's billing on May 31-June 1 at the Inn of the Beginning is also suggestive.
No proof will ever turn up, of course, so this can remain little more than speculation. But I sure would have liked to belly up to the bar at the Sand Dunes on this Monday, in the thick fog and salt, and catch some tunes.
- Jerry with Merl and/or Martin, ca. 1974, The Sand Dunes
- JGMS: "July 21-22," 1974, Keystone, Berkeley, CA