A lotta times people go to a Martin Serial list to date an Indiana model - they meant well, but.....the Indiana's had their own serial sequence.
I dunno if anyone has ever actually formulated an Indiana serial LIST...but I use www.themartinstory.com to get a ballpark age on Indianas.
If you go to their Models link, to Indiana, you can see the serial ranges of the Indianas.
That'd be my guess what is happening there when one sees an Indiana, same-side bellkeys, listed as a 1920's horn....
I dunno if anyone has ever actually formulated an Indiana serial LIST...but I use www.themartinstory.com to get a ballpark age on Indianas.
If you go to their Models link, to Indiana, you can see the serial ranges of the Indianas.
That'd be my guess what is happening there when one sees an Indiana, same-side bellkeys, listed as a 1920's horn....