There are 6 Stewart 51 S-51D 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 1999 and 2020.
N1944K
2020 Doyle Michael J S-51
Kalispell, MT
N251CR
2015 Fitch Clifford E Jr STEWART 51-D
Beecher, IL
N551P
2015 Jim C Gohm S-51
Prescott Valley, AZ
N510JP
2005 Peck John A S-51D
Shady Shores, TX
N90PK
1999 Wahl Robert H S-51D
Flint, TX
N511CG
Stewart 51 INC S51D
Cody, WY