I took some time to check the Lucas
reference book for the correct MagDyno that was used on the 1951 ES2 used. It is as follows:
- Magneto section MO1L, part number 46029 A or B
- Dynamo - E3L, part number 20013 D thru J
Be careful when looking for one by simply quoting the application, because some of the earlier machines used mags that rotated clockwise, while the one you need is anti-clock.
As Rohan suggested, it is much less expensive to rebuild an existing MagDyno than to build one from scratch. However, if you can not locate one, I can build one for you from my stock. Or, I could restore one you might find.