Numbers under paint

[dragnusa]

Ok started working on the bike I picked up yesterday. while removing the paint we found numbers underneath the paint. wondering if anyone else has ran into this before?
This is the pic from my post yesterday

Then we found this number on the down tube today

And this one on the seat post

 

[SSG]

Often bicycles use in an industrial setting like a factory are marked with numbers, but that doesn't look like the type of bike you would use. It could also be they are related to registration/licensing.

 

[B607]

An "N" number might be an ID marking from an airplane. Maybe a kid put some airplane model decals on the frame? Gary

 

[Wildcat]

I think B607 is on target. That number probably came from a model kit for a Beechcraft 35.

Quotes:
Inflight view of Beech 35 Bonanza, NX80040, the 4th Bonanza built. Beech built 5 prototypes which are identified as numbers 1, 2, 3, 4 and 5. Airframes 1, 2 and 5 were not flown, rather used for fatigue testing. Airframe 3 was the first Bonanza to fly on December 22, 1945. Number 3 used a laminar flow wing and a 4 cylinder Lycoming engine. This image shows airframe 4, the second Bonanza to fly, and the first to use the now familiar NACA 23000 wing and a Continental E Series engine. Number 4 shown in this image was used for certification flying, including dive tests to 286 MPH. This airplane has fabric covered ruddervators. Later this airplane, now certified and registered N80040, was used by Captain Bill Odom to establish a light plane long distance non-stop record flight of 4,957 miles from Honolulu to Teterboro, NJ, in March 1949. Odom named the airplane "Waikiki Beech." Later the airplane was renamed "Friendship Flame" and flown around the world by Representative Peter F. Mack Jr. Today N80040, number 4 is in the National Air and Space Museum of the Smithsonian, in Washington, D.C. Preproduction number 4 is the oldest flyable Bonanza in existence, although not airworthy at this time. NOTE that all the preproduction Bonanza's are numbered from 1 to 5, however they do NOT have the letter "D" preceeding the serial number. Once certified, all production Bonaza's have a serial number with the letter "D" preceeding the number. My thanks to Ray Johnson, for correcting my original caption. Ray Johnson owns Bonanza serial number D-4 (not the 4th preproduction Bonanza now in the Simthsonian), registered N80404. B&W, about 71K, Added 05/01/07. Caption updated 11/07/11.