I have the original harness, and will be reusing some parts of it. I am adding grounds, fixing all of the splices, and then adding all of the wiring I need for the new dash. I am also rewiring from the firewall out to the headlights and from the main harness to the rear of the vehicle. I had new wire printed with descriptions of what the circuit does, example pink wire printed with "fuel" for the fuel sender. I work in the heavy truck industry and design electrical systems and harnesses for refuse trucks. This type of labeling is our common practice and it make tracing and troubleshooting a LOT easier. Another change is the wire that is going in, TXL which has a thinner insulation, and creates a smaller bundle. Combine that with convoluted tube (split loom) and everything should be well protected.