I have made finding a complete set of clutch head drivers one of my quests. Picking through the screw driver bins at flea markets, tools at the hardware stores (the good ones), among other places, I have found 3 different sizes - Looking for 1 more illusive size. If nothing else, it is fun to look. In the meantime I borrow J. Milliman's when I need the size I do not have.
HB