If it was the pill he took on the train (with Buscetta) after the Tahoe shooting, I bet it was Miltown, the universal tranquilizer of the late Fifties and into the Sixties (the Stones sang about it in "Mother's Little Helper").
Turnbull, do you agree that the juxtaposition of the pictures I linked, the scene discussing Roth's assassination, and the final scene of the film, show a clear aging of Michael? Note the differences in hair style, the greying of the hair, the wrinkles under the eyes and on the hands, and the longer sideburns (consistent with a late 1960s time period).
