There are 5 Waco CSO 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 1929 and 1930.
N656N
1930 Waco CSO
Franksville, WI
N517M
1929 Waco CSO
Bisbee, AZ
N618N
1929 Waco CSO
Geneseo, NY
N265M
Waco CSO
Elbert, CO
N671N
Waco CSO