94 F250 drip rail fixing a leak
 

Hi folks,
As stated in the title I have a slow drip inside the cab whenever it rains. I've pulled the trim inside the cab and think the leak is coming from the drip rail where it starts just behind the windshield. See photo. Before I sand and paint the area there seems to be a material in the drip rail that has long since hardened. Should I remove the material and replace it with fresh product? This is my hunting truck so it doesn't need to be sexy, form over fashion is the motto with this truck. I just want to stop the leak.
https://cimg2.ibsrv.net/gimg/www.for...4ba8d3e992.jpg

What I would do without expert advice is to sand /clean the area and apply whatever you were going to use. After it is safe, hose it down and see what happens. If it still drips and you are convinced you are in the right area then dig or grind it out and redo it. JMO Sandy

I would sand as much rust off as your can, then spray a rust stop primer (if it's a woods truck, Rust-Oleum would be fine). Then once the primer is dry, scuff it with a scotchbrite pad and caulk with a 1k seam sealer. Lord Fusor 800 DTM is a good one that isn't very expensive. Then paint over top of that.

Thanks for the awesome replies. I'll get on it once it stops raining, which seems like it never will this year.