AC Wiring harness vs. Non-AC Wiring harness

My impression from your thread is that you are replacing the harness in front of the firewall. Check the application charts, but that harness is usually not different between AC and nonAC (at least that was true in 1970) The wiring for the AC under the hood is a separate little harness. The big differences and the substantial AC harness is under the dash, like someone mentioned earlier.