I have several stack dates for action stacks made by Standard Pneumatic
Action Co.  I'll just give you a few to help date the Auto-Art player
piano.  These are verified dates from inside the stack as well as the
case number.

108758: 1912 (double valve stack)
288641: 1913 (double valve stack)
316061: 1917 (double valve stack)
300435: 1924 (single valve stack)

As you can see, there is a discrepancy with the chronological order
as the 1924 number is smaller than the 1917.  I started keeping track
of the single- verses double-valve stacks and they indeed have a
different numbering system, so I do believe that the single stack was
made later and they started with another numbering system for that
stack.  The single stack numbers that I have are from 299698-403080.

One other interesting fact is that the factory always stamped the
bottom of the bellows with a completion date.  If the bellows has not
been rebuilt it would still be there and you can see it with a mirror
and flashlight.  It is right on the cloth where it is glued to the
wood.

So there you have it, hope this helps.  If anyone has anything
different to say I would be interested as this is all very confusing
to me as far as their numbering system.

Diane DeTar
San Diego Area, California