Glad you enjoyed them Ron. You may use any hook you like really. Those in the scans are dressed on various hooks, as these flies have been dressed at various times over a period of many years. Some I dressed over forty years ago. I assume the 3906 will be just fine.
http://www.ezflyfish.com/mustad3906.html
But I would probably go for the 3906B myself, as many of these flies tend to look a little better on somewhat longer hooks ( 3906B is 1X long) but that is purely aesthetics, and I don't imagine the fish care much!
http://ezflyfish.stores.yahoo.net/mustad3906b.html
As long as you are happy with the hooks it doesn't really matter much.
TL
MC