Thanks Tony, great info that I'll print out and keep it with my other data/info. Very useful!
The Ford GP is a positive ground system, similar to many (all?) Fords of the period.
It's the GPW that is negative ground, as per the Willys build spec.
The rebuilder - the current one, not the first one - told me the field coils were 'burned out' whatever that actually means. As the generator has only had 6V, Pos ground, put through it since I have had it, I suspect a 'paraffin overhaul', as Richard put it.
There have been a few instances during the GP build where I consider I've been taken for a ride. Expensive suspension bushes that didn't fit, 'repro' fan belts that turned out to be standard Mitsubishi with the label inked over and which rubbed-off at first use, and now a generator rebuilt with a puff of black paint and an invoice!!
Oh well, such is life ...
Mike