On my son's car, the Hotwire harness has a lot of feeds for a lot of stuff like gauge sender wires, cruise, fuel pump, and a bunch of other stuff you can use as an option. If you use the hotwire harness to its full extent, a very small body harness will be required for the rest of the car. The old cars have very few circuits, originally, Mopar only used 2 or 3 circuits, and the Hotwire unit only needs a few powered sources to run. I believe you will need fuses for: headlights, turn lights, brake/flasher lights, wipers, heater blower, and radio. My son bought a 10 or 12 fuse kit, and almost 1/2 we didn't use.

Also, don't buy the cheapest universal wiring kit you can find, there are some really cheap kits available. Stick with a name brand with tech support. If there is no phone tech support, buy from someone else. Gene