Thanks for posting that up. I've used the photos of the Military Models on your excellent site as references whilst restoring mine. Nice, detailed pictures. (-:
On the subject of the USA serial number, it's nice when this is on the frame, but I've now seen three examples of army issued Militay Models from France where there is no number. Initially, I wondered if they'd been filed off when the bikes passed into civilian hands, but looking carefully at the paint on the bb, this doesn't seem to be the case.
It's probably not possible to tell, but does the USA number on the examples you've seen appear to be stamped on before (ie, by Westfield) or after manufacture (ie, by the army)?
Looking at your bike, did the tool bag come with bike or did you add it on. Looks like the same bag as the G519. Been in discussions with bike collectors to find out what type of tool bag was issued with the WWI GI bicycle. Seems the the bicycle repair pouch at the Army Quartermaster Museum is really a repair pouch for the 1917 Browning Water Cooled Machine-gun.