69 barracuda charging issue

Are you getting 12.2 from the back of the alt when the car is running or from the battery?

You said you replaced the voltage regulator did you make sure that it has a good ground connection?

The bulkhead connectors are also suspect, especially behind the dash where you can't see them.

What does you amp gauge say? does it even work?

Also and i hate to even ask but you did double check all of the connections you have loosened removing both correct?