I was looking for something else a while back and found another interesting part that I can only speculate on its purpose. The housing is like a regular electronic voltage regulator but the connector is the familiar 5-pin ECU. It also has an adjustment screw with an arrow that looks like it says "high" on one end. The part number is pretty clear as 3501840.

It can't be an ECU since it doesn't have the power transistor and I can't fathom the need for a 5-pin regulator. Maybe an adjustable timing control?

All WAGs welcome.