It's a dual field connection, which got shortened to dual field in usage.

Difference between the old and new style regulator boils down to this. The old style regulator switched the voltage to the alternator, turning the charging on and off.

The new style varies the ground and can control the output in a smoother manner.

Temperature compensation was built into the OEM regulators, the MP constant output one does not compensate for temperature, which is the ONLY difference. Might it shorten battery life? Maybe, I ran one for years and my battery lasted for 8 years with one. YMMV.

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They say there is always the exception that proves the rule.
Don't be the exception.