Today in the post arrived two small parts that pop inside the dizzy cap of a AC Delco D204, which just so happens to be what is fitted to most Vivas, if you have said dizzy in your Viva you will know it but the terrible fitting cap design.
Anyway a trial fit to a spare distributor shows the hall ring (little black bit) is very slightly to small, but the use of an emery board or similar should make it slip down the shaft perfectly.
The controller unit sits inside under the cap where the old points and condenser would sit. All with just two small wire, one is the LT lead as per normal and goes to the coil, the other wire goes to the other side of the coil. Alas I cannot fit it to the car just yet as both wires are too short for the coil location so I need to extend the wires, sounds simple but I don’t do electrics, each time I crimp on a connector to a wire it falls off in two seconds flat! Here is how it should look when all fitted.