This is a dual point distributor; looking down at the unit with the cap and rotor off, and the points at 5 and 7 PM, the points on the left are I understand the fixed set, with the set on the right the movable set. Both sets are initially set at 20 thou full open, then the adjustable set is set to open exactly 45 degrees after the fixed set. By this means they fire alternating cylinders in the firing order.
Turns out the fixed set seems to be readily available as AC-Delco C129, part number 19106968; Standard parts number DR-1823. The other, movable, set appears to be a mirror image of the fixed set, but not so readily available. Does anyone know the original model and/or part number for the movable set?
The movable set in my car has a broken spring; it is marked Wells DR-170.