Oops, feb 11, 1970 is what I meant to type; Peter Green (original founder of fleet wood Mac) and Duane allman jammed with Garcia and the boys; unbelievable Dark Star, Spanish Jam, turn on your love light; nothing like it.
Peter Green - Green Manalishi, Man of The World, Albatross.
Also, the author and first performer of Black Magic Woman.
If as you say, he played live with Gerry and Duane, I gotta find that.
Although, Peter was probably pretty well fried by 1970.