After doing some more research online, I have come to the conclusion that he must have created his own mold and used the Rub-R-Mold to create his own mold for life-like legs and claws. The photo in the book shows an incredible sample of a fly that is very lifelike. Looks like the real thing.
I will keep checking this to see if anyone has any other ideas, but I am pretty sure it is from his own mold.
-Daniel