I photographed these M100 Cargo Trailers at the Tillamook Air Museum, Dubois at the Western Antique Aeroplane and Automobile Museum (WAAAM) in Hood River, Oregon.
These are 1/4-ton trailers, less robust than the larger 1 1/2-ton M105 Cargo Trailer. The M100 also is very similar to the 1/4-ton Bantam T3 trailer.