Can't see it being the new reg/rec so next is check the alternator coils.
Should be no continuity from any of the yellow windings to earth. Between each other the resistance readings should be between 0.1 & 1.0 ohms. This is with the reg/rec plug disconnected. The plug going into the reg/rec should have 3 yellow, 1 green, 1 red/white and 1 black. Yellow is the windings. Green should be earth, black ign and red/white live.
Should give you some ideas where to start.
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