[ Ref. David Krall in 250307 MMDigest ]

David, that is a late Standard Pneumatic Action Company design --
an unfortunate design, I am sorry to say. Note the tracking pneumatic
which is of the usual design on a "Standard".

The stack with those arms and all is designed to be compact in order to
fit into smaller pianos. I see in the photos that some of the arms are
broken, which is typical on those.

Is this for a customer of yours? Maybe you can get at least 80 of them
put back together for the job. If that is what you are needing it's
going to be a challenge to find a parts action. But then again, perhaps
an MMD reader will have some of the arms for you!

Best of luck,

Ben Gottfried - Ben's Player Piano Service
Richfield Springs, New York
https://bensplayerservice.com/