Reverse lights not working, need wiring harness wiring diagram

I need some help with this repair! The truck listed above is a C1500.
No reverse lights, bulbs good, fuses good, so I'm going to change the park/neutral safety switch located at the bottom of the steering column. However, I found the problem before removing the old switch. Someone removed the wire harness for the reverse lights. I don't see the harness hanging anywhere. Pretty sure the harness that is connected isn't wired correctly as well (blue and green)! So, I need to know the wire colors for both wire harnesses for the correct installation. SOS