Need to wire up an electric fan on my 360...

I agree on getting a pre-wired fan-relay harness. I bought 3 approaches. An aux fan wiring kit for $15 on ebay. This was a factory recall kit for a GM SUV in AZ that dealers started unloading cheap, so bought 2. Just the relay and wiring harness, no temp sensor so I bought a temp switch separately on ebay (hard to find a <200 F one). Then I saw a Hayden 3651 kit on rockauto for $25. This is the better model w/ screw-in temp sensor and adjustable setpoint that you see for $50+, sometimes relabelled Jegs or Summit. Before above, I bought the solid-state relay used on my 2002 T&C minivan ($29) since it drives 2 fans and should last longer, but more work to wire, so will probably just keep as a spare.

The fan circuits can run stand-alone quite easy. They run the control thru the engine computer in most modern cars, but mainly just to monitor failures. I saved some info on wiring it so the fan also comes on w/ the AC compressor. As I recall, that requires another relay (can be small since just for logic). If you install an engine controller like a Holley Commander 950, many can control the fan.