Below is not 100% reliable and the information below applies mostly to wooden body resonator Dobro guitars. For example I own a Dobro metal body M-62 with the serial number 1832. Again, without having seen or heard the instrument, I have no opinion on its worth, beauty, playability, tone, value.
If you look further down that same page that I referenced, it gives serial number information for later model Dobro® guitars. OMI guitars the last letter was either a D=wood, B=metal. I'm having trouble decoding the serial number on my dobro. Along with its complicated manufacturing history, this makes establishing a particular Dobro’s value challenging. Its popularity has steadily increased, so Dobro-style resonator guitars are now built by a variety of new and established instrument manufacturers, as well as custom luthiers.
