ACUF, what is the failure mode of the original? if you have an external regulator, you may only need to replace the brushpack with an internally regulated brushpack. This would eliminate the original regulator and the harness between it and the alternator. I replaced my alternator (12V system) with one from an 80's model VW Golf which has the same external dimensions (clocking) as the original. The one I installed is a 90A rather than the original 55A so I upgraded the wire size on the B+ wire to the battery and transferred the original pulley from the old alternator. I have even seen a few of these that had the W terminal for the Tach output.