how to find the type of piano

[Doepke Family]

I have a customer with an old upright that has serial number as the only
identifying feature.  There is no name or label, and if there was one on the
fall board, it has been painted over.

The number on the plate is 120912.

How can I find out what type of piano it is without a name or a label?  Am I
stuck?

Brian