Not sure what year was the 50th anniversary, but the 1972-76 had a Lo- Tension Magneto. Flywheel magnets pass by the driver coil with both sets of points closed. A voltage/current is generated in the driver coil. One set of points open, and the voltage collapse creates a higher voltage which is the "Lo Tension" part. That voltage is sent to the external coil where it is increased and sent to a spark plug. Main thing to realize is that BOTH sets of points must be grounded (clean) when closed.
