chris, i had a healthy water leak on the passenger side as well. it ended up being a crack in the sealant on the top of the cowl all the way to the drivers side. where the firewall comes up and then goes horizontal on the top of the cowl, there is an area of factory sealant that they gooped up at the seam where the firewall and cowl and such meets at both ends (driver/passenger side) of the cowl. anyhow, there was a crack in it that was letting quite a bit of water into the truck. to troubleshoot it i had to pull the carpet back and get a water hose and start running water to find it. once i found it, i scuffed it up and sprayed some wd40 down the crack until it ran into the cab (try and head off any corrosion that it may cause from water being between body panels) and then cleaned off the top of the cracked area with brake parts cleaner. i got some windshield adhesive, the 3m stuff, butyl based, and gooped it up over the factory sealant, smoothing it down with a putty knife. got that at the parts house. i went ahead and did the passenger side while i was at it even though i didn't see any cracks in the sealant there. then i shot some rattle can paint to kinda color match it so you wouldn't see it. i've heard that you don't wanna use silicone based caulk cause it can cause corrosion from the acetic acid when it cures. anyhow, that was where mine was, as well as the cowl screws on the passenger side, and the rear barn doors. i also went ahead and changed the weatherstripping around the doors and rear doors, and as far as i know i'm high and dry now. but put some extra scrutiny in that area i was talking about, may end up being a common place for leakage. good luck man. branndon.
