Preferred Voltage Regulator for 1970 E-Type?

[E703SU]

The originally fitted Lucas 4TR regulator for the 1970 E-Type is Lucas part# 37423. But a 1983 parts list from Jaguar shows it as # 37585 for the '70 & '71 4.2 E-Type. Presumably these two parts are essentially the same, though there must be some difference between them for Lucas to have changed the part number.

Does anyone have any information? Maybe the 37423 is adjustable while 37585 is not? Would there be any reason to prefer one of these regulators over the other for a '70 E were both available (ignoring the option of just getting a NCB144 regulator which replaces both these and others)?

Thanks,