Dimitry
The only reference material I’ve found really helpful regarding what zippers were used is Eastman’s A2 Manual. From what I gather Bronco used only crown zips for this contract.
M-42 Talons are also seen on originals from Bronco.
You can always verify information on JCs site as well, he has seen hundreds of these bad boys...
http://www.goodwearleather.com/pages/a2_bronco.html
DD