* 6-volt system: Uses a 6-volt coil that produces a lower voltage spark. The distributor itself is designed to work with this lower voltage, including the points gap, condenser, and potentially the internal resistance.
* 12-volt system: Uses a 12-volt coil producing a much higher voltage spark. A 12-volt distributor may have different internal components (like a different condenser or modified points) to handle the increased voltage. Simply swapping a 12-volt coil onto a 6-volt distributor could damage the distributor components. Conversely, using a 6-volt coil with a 12-volt distributor would result in a weak spark.
In short: You cannot directly interchange them. Using the incorrect distributor will lead to poor engine performance or even damage to the ignition system. You need a distributor specifically designed for the voltage of your electrical system (6V or 12V).
