Your pulsating electrical problem is most likely caused by poor brush contact in the alternator, either due to worn out brushes or a groove worn into the slip rings. The brushes and regulator are combined in a pack mounted into the back of the alt. You can check the brushes for wear by removing the pack and measuring how far the brushes extend out of the holder (it's supposed to be something like .22" min, but don't quote me on that). You can replace the whole brush-regulator pack or buy just the brushes and solder them in yourself. If new brushes don't fix it then the slip rings are likely worn. You can take it to an alt/starter shop for repair or disassemble the alt yourself and carefully machine and polish the groove out of the skip rings.