Jared, the VSS has a smooth tapered bore that snugs again the upper speedo assembly and O ring. The O ring is most likely the source of the leak, either from being old, or the VSS shoulder nut (22mm) isn't fully snug. Get under the car with a open end wrench and see if it'll snug down, if not, remove the VSS and put a new O ring on the speedo. It's just a couple of bucks. p/n E1FZ-17383-A mark