Identify this item?

I noticed this metal disc laying next to the distributor cap. I have no idea what it is. Can anyone help me identify it?

Looks like some one has added some sort of outboard electronic ignition module.

That looks like the ballast resistor that was under the coil in the earlier ignitors. Later ignitors did not have a ballast resistor. I guess it was built into the coil or the coil was designed to take the full 24 volts. I have an NOS ignitor, in the box and it does not have a ballast resistor.

Agree that is an external ballast resistor. Early coils had the external ballast resistor that sat underneath the coil in the ignitor. New coils have an internal ballast resistor and are taller than the early coils. My guess is that the PO put in a new coil and didn't know that the external ballast resistor was no longer needed and wired it in. But because the new coil is taller it had to be moved external to the ignitor.

Check if the coil is a newer style (fills up the ignitor space). If it is then you can relocate the external ballast resistor to the spare parts bin.