62 c20 generator to alternator help needed

[jcramsey]

Trying to figure this out. I know it's not that complicated but I'm missing something. Everything I've read says take the brown wire running from the firewall to the voltage regulator and run it to the #1 terminal on the alternator per the diagram below. I have a brown wire from my generator to regulator but I don't have a brown wire coming from my firewall...is a 62 color scheme different? Just trying to find the right wire for my gen light. The harness from my firewall has dark green (horn), a light green and a tan (headlight) and a large gauge red and smaller gauge red which both run to the same terminal on the voltage regulator. Can anybody help a wiring dummy out?