The Three-bearing Head model in use at the L.S. Starrett works in Athol, Mass. where over one hundred similar Ames bench lathes were employed.
A detailed picture of the Three-bearing Head can be seen  here.

Once a commonly available accessory for small lathes, the tailstock-mounted indexing turret was a simple and economical way of producing small batches of components.
An ordinary screw-feed tailstock barrel would have slowed the process up more than somewhat, but if lever or rack-operated, and with light work, respectable rates of production could be achieved with very simple tooling.

Six-station, hand-indexing Turret  and Lever-action Cross Slide.
The indexing plunger by the rear pulley flange is clearly visible.