Wiring harness replacement

Yup. There were wiring changes along the way in 70-74, so probably the BEST thing would be to pull the old one out, lay it and the "new" one out where you can stretch them out and compare connectors, colors, and actually take an ohmeter and "ohm" the thing out. This is not as big a job as it seems, especially with the factory shop manual.

The 73 diagrams are both easier and harder to follow, depending. The "easy" part is that t here's a separate index in the rear to tell you what each connector looks like and where it goes