I just did the weatherstripping on my girlfriend's '65 and after, I think it leaked worse than the original! The key here is clear silicone sealant, and lots of it. You must remove the outside trim to do this right. Just make a nice fat bead the whole way around the outside of the strip where it meets the body and then make another bead where the glass meets the strip. The trim should cover up both beads when you replace them (which are a real pain). Also, let the silicone dry for a few hours before you test for leaks.