These gauges are plug and play with the RF harness. The instructions are if you are using the OEM mustang harness. The RF dash harness has the connectors already installed and the wires are labeled. There will be a single yellow wire with a connector labeled volt I believe for the voltage gauge. The others are also labeled with connectors. So that part is simple. The only tricky part is the transformer box for dimming. It has a daisy chain harness that each gauge will plug into along with the dimmer dial and the 2 power wires that you wire in. The RF instructions cover this and it’s easy as they get power when the parking lights are turned on. If needed I can shoot a pic of where it hooks up.