Pictured above is my original 1930 Michigan Manufacturer license plate, M-306.
These 'M' plates were issued to vehicle manufacturers for their use in the design, development, and testing of engineering vehicles owned by the company.
If you study original Ford factory photos, you will see these type of 'M' plates on most of the Model A's. Most cars in photos are also wearing the same few numbers, in other words, sharing a limited number of company owned license plates.
I have not yet found an original picture of any make car with this exact 'M' plate number. It is likely it was not owned by Ford, but instead by another company such as GM or Packard, etc., or possibly an OEM parts supplier.
Nonetheless, it is a very interesting and scarce Model A era collectible!
Pictured above is the 1931 Michigan Manufacturer license plate, M-5, as seen in numerous original 1931 Ford Motor Company factory photographs of Model A's.
This 1931 M plate is owned by a fellow collector, and has been repainted and restored, whereas my 1930 has original paint.