When it comes to wiring, if you can get your hands on the proper diagrams you’ll be much better off. For vintage Mustangs, wiring diagrams are as close as your favorite Mustang vendor and have been reproduced in full color. For late-model owners, the best course of action is to find an Electrical & Vacuum Troubleshooting Manual (EVTM) for the year you are working on. These were produced by Helm, Inc. (www.helminc.com) and some manuals are still available from Helm—even Mustang II. They are easily found on eBay, Craigslist, etc. as well.