My 72 k5 blazer is not reading 14 volts when cranked. I replaced the alternator, new battery, new wiring harness and I can't still get it to charge. Eventually after driving it with the headlights on the battery will die and I have to recharge with battery charger. When you take the positive off the battery it will also die. It has to be a wire where do I start? I've checked the grounds. The guy at the parts house wanted to no why I had a voltage regulator on the core support and one built in the alternator, a total of two. I'm kinda curious myself. Thanks in advance for any suggestions. I also posted in the Garage. My backup lights don't work either. Is there a back up lamp switch somewhere for a 3 spd I can check?