The general rules first
- A serial number identifies the individual instrument. Patent numbers, model numbers and size markings are not serials — the commonest dating mistake is typing one of those into a decoder.
- Plates are metal; labels are paper; some numbers are stencilled in paint or stamped straight into wood. If nothing shows, dust and a raking light reveal a lot.
- On most brands the serial sits where the service technician needed it, not where the buyer likes it. Expect to lift lids, open backs or kneel with the flashlight.
By maker
Hammond
On 1970s organs and later: under the lower keyboard, left or right side. Older consoles hide the plate elsewhere on the cabinet. Watch for the decoys — “Hammond” also built industrial enclosures and wrote typewriters.
Leslie
The serial lives on the amplifier chassis inside the cabinet. Early cabinets carry plain metal tags with a bare number; later ones use foil tags with FA/FB prefixes. You will also find pencilled dates on the inner walls from previous owners — and for the exact year, look for the stamped code with a julian day and year on the lower baffle, or the week-year code on the motor (7245 = 45th week of 1972).
Allen
The model/serial plate is screwed to the inner side of the top rail across the back — lift the top (screws underneath, at the sides) or remove the back panel and look near the top.
Rodgers
Under the keydesk. Literally: lie on the floor and look up at the underside of the keyboard assembly. On 1980s-and-newer instruments the serial has seven characters and starts with a Z.
Conn Organ
The identification tag sits on the underside of the keyshelf at the treble (right-hand) end. Model numbers start with 3–8; 650-series are the three-manual theatre organs.
Lowrey
The plate is usually under the manuals — bring a flashlight — or on the right under the bottom keyboard. A stamped date sometimes waits on the original bench seat. Late-model Lowreys code the date into the serial itself (letter = month, first digit = year).
Estey
Estey almost always glued its label to the top of the sound board, visible after removing the back panel (and a layer of dust). Serials are 5–6 digits; on Estey & Green melodeons 4-digit numbers are real serials (1855–1863), but on later reed organs a short number is a construction mark, not a serial.
Mason & Hamlin
The trap of the archive: on these reed organs a 4-digit number is a catalogue style number (style 2253 = case 169, five octaves, ten stops), not the serial. The serial is the long number.
Yamaha Electone, Thomas, Gulbransen, Kimball, Baldwin, Wurlitzer
No reliable public plate-location notes surfaced in our research for these — the honest answer. Start with the keydesk underside and rear rail; owner’s manuals (often archived online) show the “name plate location” diagram for the model.
One more reason to find it properly
Plate photos are welcome at our contact address — corrections with sources get priority, and every photo helps the guides. No one in this niche has published a proper photo guide to plate locations; we say it plainly instead of pretending otherwise.