The pic is from "Love Devotion Surrender" sessions, Doug probably took the pic while Carlos fooled around on his bass. It was his main axe during his days with Santana, David Bowie and Billy Cobham/George Duke band but the mods were probably done by his predecessor, David Brown, who is seen playing it on Soul To Soul festival in Ghana, 1971.
I wonder where it is now? Doug Rauch died in 1979.