There are 5 Waco QDC aircraft on the U.S. registry that TailWiki has a page for. Every one is built from the public FAA record — year, serial, engine, home base, and registration history — and owners and pilots add photos, trips, and stories on top. The ones listed here were built between 1931 and 1932.
N12438
1932 Waco QDC
Groveland, CA
N11470
1931 Waco QDC
Jordan, MN
N11473
1931 Waco QDC
Sonoma, CA
N11489
1931 Waco QDC
Piqua, OH
N11443
Waco QDC
Zanesville, OH