Curious:

This is an interesting harp. It has all the characteristics of a Model 15B Berkshire harp including the logo, the rectangular buttons and, especially, the complement of chord bars. Only the Berkshire model included the Eb and F7 chords. These were manufactured from about 1967 to 1978.

But, the way the strings are identified at the bottom (the end away from the tuning pins) is wrong. Nearly all autoharps have some sort scale resembling a piano keyboard at that end or they are entirely unmarked. The individual names of the strings on your harp were only used on special models made for specific customers such as Music Educator's Group (MEG) or Monntgomery Ward (Airline models).

So, this is either some kind of special model that we are not familiar with or it has been modified.

Bev and Jerry