here is part of a email we got from the martin museum: Hi,
The YB-10 and YB-12 were the same aircraft with different engines. The YB-10 12 were considered pre-production versions of the B-10 for testing. They were all part of Martin design M-139. The drawing is certainly original and...
just wanted to share a amazing find. a original blueprint of the b10 bomber. we have taken it to a couple of museums and they verified it original. for what i understood this blueprint was one of dustin carter's collection piece. the blueprint is 81 x 36 inches. :)