Hi,
After spending hours looking for a texture to change my USAF E3 to a NATO, I finally decided to jump in the world of "creators"  ::) and proceeded myself to make my texture... This is my first experience  :D
Based on the USAF model, I erased all markings and designed the NATO markings for the serial number LX-N90443.
In the attached archive you'll find the Texture folder and the aircraft.cfg update.
https://www.dropbox.com/s/8i84gcgouqmzeeg/Texture%20NATO%20for%20E3.jpg?dl=0
https://www.dropbox.com/s/972fuisgexfszgq/90443-left%20side.jpg?dl=0
Download the archive from here: https://www.dropbox.com/s/fmfew8d6kflvc6s/CS-E3%20Texture%20NATO.zip?dl=0

I hope you will enjoy it in FSX (for sure, I use it).
Bruno