B400 voltage

[PEU186F]

That's the challenge. Often there is a hint that regulator and dynamo must be compatible.

I understand that different manufacturers, e.g. Lucas and Bosch, used different principles to regulate the output of the Dynamo, so neither the regulator or the Dynamo are compatible across the manufacturers. But I am fairly certain that any Lucas built regulator will be compatible with any Lucas Dynamo as the dynamos always work on the same basic principles. With the possible exception of Rolls Royce / Bentley who occasionally dictated their own views on how things should be done