The diagram in your instructions that came with the new wiring harness is rather "flaky".. First, you need a factory wiring diagram pertaining to your truck and a factory diagram for a later model having an internal regulator.. Compare the two and you will understand the wiring modifications needed.. Take a look at this thread, post #2.
http://67-72chevytrucks.com/vboard/s...ire+alternator It's for a dash that has am ammeter, not a light.. Search this site for a wiring diagram for a charge light if that's what you have..