That looks similar to the A127 I fitted to my car although there look to be some differences, I don't have that white block with "tested" and a lead which looks like it's going to earth for example.
On my car the OEM unit had a seperate earth lead whereas modern alternators ground through the body so the black earth lead will be redundant.
The plug Alex has posted a link for is the one I used, basically the large terminals are the charge output to the battery via the ammeter, the small one is the field terminal.
When my original unit failed I didn't bother trying to fix it but instead I fitted a Lucas 17ACR unit with around the same output. That was a tight fit against the luggage tray and I later replaced it with a higher output Lucas A127 unit which is smaller and comes in several output levels. The lowest output one (55amps IIRC) use the spade terminals, the higher outputs use a bolt on lead instead. I made some notes for my records at the time and have attached the pdf which shows the wiring terminals and what I did back then.
Brian
