Just to close off this topic and answer the question, I have recently replaced my original Lucas 11AC Alternator with an uprated 55 amp Lucas 11AC from SNG Barratt. I could have gone for their Self Regulating 70 amp Lucas 11AC unit, but I wanted to retain the original 4TR Alternator Control unit which is mounted under the heater fan unit. The Self Regulating unit does not require the 4TR unit, but requires minor wiring modifications.
I attach a couple of photos with the SNG Barratt guide photo showing the thick Battery connection where the Brown with White trace cable connects. It also shows the two Field connectors where the Brown with Green trace cable and the Brown with Purple trace cable connect. Of the two Field - and Field + terminals, the Field + terminal is the one inside a white plastic shield. Despite their names, they are not really sensitive to polarity, so you could plug them in either way and they would work. However, to be totally correct, by turning on the ignition to see which wire has 12 volt +, this wire goes into the shielded terminal. In my case the Brown with Purple trace is the Field +.
My 1967 4.2 car has the 3AW Warning Light Control mounted over on the chassis rail over on the other side under the carburettors which connects to the Ignition Warning light. In my case, this needs the smaller spade terminal connected to the 3AW using a White with Brown trace cable.
I trust this assists.
Regards,
Dave
....Steve
