I rebuilt one of these many years ago.  Like you, I had some disbelief
when told of such an instrument.  The drawer was identical to a Model B
Ampico with the exception of the Duo-Art tracker bar.  The rest of the
mechanism (stack, pump, expression devices, etc.) was typical Duo-Art.
The instrument was in a plainer case than the one shown on eBay.

I understand that this was a late product that resulted from the merger
of Aeolian and American, and very few where made.

Craig Roothoff
Escondido, California