National Air and Space Museum Aeronautics Division
Chuck,
Try the above. It's the Garber Facility in Maryland, just outside DC. They have everything from blueprints of the P-51 series to flight manuals, etc. They are the RESTORATION service for the NASM. Slow, thorough and if someone has it they would or would know who does.
The National Air and Space Museum Archives is the repository of thousands of aircraft and spacecraft technical and scale drawings, donated over the decades by manufacturers, the armed services, and by individual illustrators. Most drawings are available for reproduction. Lists and order forms for several drawing collections are available for download or by mail, but these listings represent only a small percentage of the Archives' drawings; see Miscellaneous Drawings on Paper for information on ordering "unlisted" drawings.
MiG
and as a backup, http://www.nationalmuseum.af.mil/