[Tony Smith]

Brian, you need to re-check your parts stock! The basic Ford number for voltage regulators is 10505, not 1505.

These were a common part across many Ford vehicles, and not simply restricted to CMPs or even military vehicles. In the CMP parts lists, there are an amazing 9 variations of these regulators listed, with differences being for:
1. Pos or Neg earth,
2. Battery Specific Gravity (a new concept to me, I thought all batteries ran the same spec grav for "charged" or "discharged" state!), and
3. Country of manufacture.

I have in my possesion a "Made in USA" reg, a "Made in Canada" and an ENFO "Made in England". Only the English one appears slightly different (and that may be because it is possibly Post-War manufacture), yet the mount holes are identically spaced and will interchange with the North American versions. It is not listed in the CMP Spare Parts Lists, but I also have references to a 35amp regulator and a 50amp version.

Why the option of Pos or Neg earth? As stated above, these were a common item across many Ford models, for export to many countries. Even the "Standardised" CMPs were specified differently for particular contracts to certain buyers. I would presume the contracts for supply to Britain and possibly India would have followed national preference/practice at that time for Pos Earth vehicles for compatibility with existing fleets, while contracts for supply to Canada would have followed North American preference/practice for Neg Earth. On Australian Blitzes, I have seen both Pos and Neg earth systems, so our stock of CMPs would have come through a variety of supply contracts.