Which alternator do you have? The battery sensed alternator I described is the later type. Lucas 18ACR or similar, that’s internally regulated. Or do you have a Lucas 11AC? That is externally regulated with a 4TR regulator, and has a 3aw module to operate the light and a 6RA relay relay to disconnect the alternator when the ignition is off. The round can could be a 3aw module. The systems are wired differently.