...... It looks like it has some kind of power feed added on in addition to the indexing, but not sure if that was originally something powered by the shafting, or a shop improvement?
In answer to my own question, catalog states that 30" and bigger plainers were furnished with power elevation that derived it's power from a friction clutch on the idle pulley of the jack-shaft. Looks like they just had it belted to a little gear motor when they added the overhead drive motor to the machine.
On another positive note, while missing the shifting parts, the overhead pulleys and hangers are exactly like the catalog photo's. It's not the "2nd belt" design however. From what I read, it sounds like both set-up's do the same work, the 2nd belt drive is just more efficient and smooth operating.