Leaks around windshield gasket

I just pulled the rear glass out of my 68 fastback and i found a rope like substance with a sticky tar like adhesive on it. Pain to get off. What I am getting to is I used the Butyl Ribbon on many newer cars that i have repaired over the years. Very close to what was in mine! I put a bead of this in the channel were the seal slips on the glass, this will seal this area completely but remain flexible. I then rope the edge and pull the rope to insert the glass into the veh.. This is were it gets relavent to your issue! Get a a cartridge of 3M Urethane and just nip the tip off 1/16th" to allow for a small bead of urethane. I use a trim tool to lift the edge of the seal up enough to get the tip in without making a mess. Pull the trigger on your caulkgun and work around the W/S... Not done yet!! Get some 1 1/2" blue tape and stick it to the seal in the corners and pull tight until it meets the pillar. Tape it to the pillar and let it sit for 24 hours. DONE!