Ok, 5+ years down the road and another "fine toothed comb" perusal of this photo from back on that other thread, I had mistakenly identified the blonde guitarist in front of Gregg Allman's organ as Duane, but THAT is actually Danny Kirwan. And, I'd identified the person behind drummer Bill Kreutzman as Allman Bros bassist Berry Oakley...that actually is Duane Allman.
So again, from left to right along front of stage:
Mick Fleetwood (arms raised), Peter Green, Ron "Pig-Pen" McKernan, Bob Weir, Danny Kirwan, Gregg Allman.
Left to right rear of stage:
Jerry Garcia, Bill Kreutzman (drums), Duane Allman, "unknown tambourine player", Butch Trucks (drummer with hat), Phil Lesh....and probably Mickey Hart with back to camera (waving drumstick) to the right of Gregg Allman