You can't get a harness for Fords that plug into the back of your F900, what you get is a harness the plugs into your Ford harness and that gets wired up to your F900 harness, it's easy to do and can be done outside the vehicle for the most part then just plugged into your Ford and the F900. You can find these at Crutchfield.com, Best Buy, and other locations. As far as the VSS wire, it makes your unit more accurate but isn't required. It's usually an easy connect on most fords because they have the VSS wire right at the radio harness, it's usually the Grey wire with the Black stripe but could be different on your particular vehicle. Let me know your vehicle specifics (model) and I can give you a little more info.