I have put a 71 ss dash in my 72 chevelle. I have the 71 dash wiring harness that came with the dash. My question is my 72 has factory air and the 71 I got my dash and harness from did not have air. What will I have to do to get the harness I have to work with my a/c dash. I was hoping maybe GM made just one harness with the wiring for the a/c and just did not use the wire for the a/c on non a/c cars. If not does anybody know how to add the extra wires for the a/c?