[Grumpy old man]

I used 3M self leveling sealer (2 part epoxy #08307) So did I . You don't want it to overlap any masking tape . Before you start shoot a small amount onto some card board to see how much it flows and how fast it cures . Drip rail seal is what these 2 products were designed for , There really is no reason to use anything else to finish off your drip rails . I was able to do mine and still have a bit left over using 1 tube . The only place I masked was at the bottom of the drip rail to catch any run off from the back of the rail . I started at the center and slowly using a Z pattern with the tip of the gun in the sealer ( to prevent air bubbles ) and laid a bead down . Just remember it's going to begin to cure pretty fast so you want to move with purpose and get to the other side of the cab so the center sealer matches the side you've already done . You'll spend hours cleaning out the rail then priming and sanding before the sealer goes in and your done in 10 minutes .