I think it's MD, but please wait on some others. Is the "doubling" only on UNITED? The reason I ask is there is a very rare and valuable 1966 DDR that looks like this. I'm pretty sure it's MD. I can't make out the doubling on the inner curve of the D, and it seems to take away from the letters. I also can't make out any doubling on any of the other words. Check out these links: 1) Wexler - http://doubleddie.com/814618.html 2) Coneca - http://conecaonline.org Scroll about half way down. The heading says " Third 1966 Doubled Die Rev. Cent Found" Don't get your hopes up, but best of luck!