I wired an SI10 into my 64 and it was pretty easy. It energizes at an idle and is rock solid at 14.64 volts. Much better than the old external regulator system.
If you look at the picture, I still have a regulator but it is dummied out. I tied the 4 wires together -terminals 1 and 4 and terminals 2 and 3, then hooked them at the alternator at the 1 and 2 posistions.I ran a new 10 gauge wire for the 55 amp alternator and tucked it into the convoluted wrap. No muss no fuss.
The Idiot light works as it should also, plus the number 2 terminal (voltage sense circuit as mentioned before) is a long enough run to work correctly.