What period? For what airplane? For flight duty or on the ground? Things changed fast betwen the 30s and the 50s. And by the time they were USAF they were not wearing those kinds of clothes when flying IIRC, that is more USAAF. A useful source for modeling military guys are the line of books by Osprey. Something like their "Modeling WWII Figures" might help or have links to sources. Also look at something like "U.S. Military Combat Aircrew Individual Survival Equipment : Ww II to Present, a Reference Guide for the Collector" "A detailed study of United States Air Force, Army, Army Air Force, Navy, and Marine Corps aircrew survival equipment. Items covered are: survival vests, leggings, and chaps, life preservers, survival (ejection) seat and back pad kits, personal survival kits and first aid kits, etc. Tag and label information is provided for each item., over 170 b/w photographs, drawings, 8 1/2" x 11" A large library would be helpful, particuarly a university library.