Douglas NO-1 and NO-2 are early designations of USAAS, so the serial numbers beginning with A- (that belong to US.Navy) are wrong.
A-6431/6433 are Naval Aircraft Factory NO-1/NO-2;
A-6663 is Lowe-Willard-Fowler MO-1;
A-6664/6688 are cancelled contract for Lowe-Willard-Fowler MO-1.
Perhaps the photo refers to NAF NO-1/NO-2: i think that the Douglas NO-1 was never built. 03/05/2004 @ 06:22