Just finished 503. Ugh. Do not want to ever do again, though this time I was quicker and less messy about it having learned from doing the job yesterday on the other car.
The stuff I used I picked up at Autozone. It was longer than 12" strips for sure. Came in a box and had enough in one roll to do the two windows on both cars. I made sure to put the "joint" at the bottom of the windows.
When I pulled everything apart, the passenger side was missing a good 4" or so of sealant on one side. No wonder there was so much wind noise at freeway speeds. It would also leak water like a motherf*r everytime I washed the car. It had all "melted" and conglomerated at the base of the window, making for a huge mess. Some of that sh*t had even made it to the inside of the plastic interior panel, so whenever I tried to clean the inside of the windows, my paper towels would get that gunk all over them. Now both cars are air/water leak free and have a nice clean bead of sealant around them. Glad it's done. Hopefully it lasts another 20 years.