With my 66 mustang the front one does not have the chrome finish put on yet. There are some leaks & I have tried silicone which doesn't work well. I just tried some seam sealer which adheres better. I have a tube of 3M window weld ( 08609 ) that I got from Mustangs Unlimited, they said that will work. With the rear window I have removed the moldings and used silicone and the put on the moldings with limited success. I have owned a Falcon & a 63 Comet and have had similar problems, at least if I can find where the leaks are I can seal them rather that remove the glass and start all over again. Any thoughts?