Go to Google and enter "Oklahoma National Guard"--I checked it out and found some good info and pictures you will find useful. You can even enter "Blackhawks" after the word "Guard" for more specific info. There was one good side view, taken on 4/8/2006; it showed no specific National Guard markings (sometimes might have the 2-letter state I.D., followed by "NG"--such as:" OK-NG "above or below the tail number; or the previously noted emblem on the pilot's doors). The tail number was "24416". Check out this web address for the picture: www.flickr.com/photos/oklanationalguard/3638881512/sizes/l/in/photostream/
Also, you might try contacting one of the units flying the Blackhawk (the 150th Assault Battalion is one in Oklahoma) and tell them what you are doing and what you want; as long as it does not violate any security matters, they are usually very cooperative and helpful. Hope this helps and Good Luck!