I have an 81 firebird and I'm working on fixing the hacked up wire from previous owners and I can't seem to find a diagram that would tell me what each color wire goes to from the firewall engine harness the picture I attached isn't of my car I just attached it so everyone will understand what I'm talking about I'd appreciate any help thanks

 

Hi, the bulkhead connector splits into 2 parts when you remove the centre bolt and pull it out. They kinda clip together to form a single plug that only goes together one way.
The one side has all the engine connections (engine harness) and the other (front end harness) has all the headlights, indicators, horn, etc.
Using the diagram below, you can work out where each one goes. That's what I did.
I also have a full wiring diagram that I will try post below this.

 

Wiring diagram attached