This is the classic example that should get people less focused on gear and more on ability. Sure they are all playing vastly different instruments, amps and cabs and yet they still basically sound like Garcia, Weir and Lesh.
I once heard a recording of Carlos Santana on a Squier Strat through a pig nose amp. And he still sounded like Carlos. Not to say that I am not obsessed on recreating Garcia's rig and sound, but the fundamental truth is that the sound is not in the gear but in the fingers...
"And I'm here by the road, tied to the load, that I picked up in ten thousand cafes and bars" - Barlow