Model B speculation dates for Mason & Hamlin Ampicos have been
a lengthy quest.  I found Mason & Hamlin SN 39906 RA Mahogany.
It was shipped out of the factory on 3/25/1929.

Interestingly, there is a two week gap in the M&H production logs of
no production/shipping between 39849 (3/9/1929) and 39906 (4/25/1929).
And after that date the volume of Model B's increases.

This 39906 Mason & Hamlin is in my cousin's house in Texas.  She
purchased it about 10 years ago.  The model B is definitely
original and is slightly different in a few ways and the provenance
is corroborated from its two prior owners.  It was shipped to Ampico
Hall in St. Louis originally.

It has been restored and plays beautifully,  Of course, upon my
insistence, she also has a Knabe Ampico B, Louis XV in Walnut, in
the same living room.

Ken Long
Dallas, Texas