The book is indexed to the characters and not the guns - don't see anything right off the bat. Another book by Backyard Buckaroos has quite a bit on The Mattel Fanner 50. First came the Fanner 45, almost a perfect replica of a SAA, made '59 to '62. The 50 follows the general lines but is obviously a toy with an oversized trigger guard, offered with both revolving and non-revolving cylinders from '59 to '68.
Branded 50 models include the Planet of the Apes, 1960 only, antique bronze finish with black Impala head grips and considered quite rare; also the Cowboy in Africa, '62 only, chrome or black with white Impala head grips. The Agent Zero, '65 to '68, has black finish with engraved metal and walnut-style grips. An Agent Zero 38 snub nose was also offered '65 to '68, black with black or gold cylinder and the "Shootin' Shell" system, where a single cap was put into a toy bullet in the revolving cylinder.
Mattel started the Shootin' Shell with the Fanner 45, used it in some 50s and finally called the line Shootin' Shell, often with stag grips. Toy companies, even big ones like Mattel, made design changes with very little fanfare and almost no records survive. This may be why a certain kind of collector finds them so fascinating. They are not people who can't afford real guns. Some of these things bring big bucks, although I suspect the market has cooled considerably since the financial crisis.