Wanted to share my success stories.

My cab would puddle water on passenger floorboard when raining and also drip from the top of the windshield on passenger side. So along with not getting great heat in the cab I set to work on sealing them up. I bought this at Advance auto.
https://www.permatex.com/products/ad.../?locale=en_us
and it flowed really well. I removed the trim ring around the windshield and washed and scraped all of the dirt and goo that had collected there from being under a tree. while running water over the windshield I also ran it down the cowl and behold, leaked like a sieve at the firewall and the air conditioning box.

Getting the cowl off was a major pain. However if you dont want to remove the hood, I loosed the hinge bolts (the bracket hinge, not the spring one) to allow wiggle room on both sides. With the wiper arms removed and hidden vertical screws in the cowl removed, you have just enough clearance to remove the cowl. I vacuumed a tree worth out of the driver side cowl drain area. I washed it down with water for a few minutes and allowed to dry overnight. Came back with black Flex-seal I got at Harbor Freight and went over the seams I could see. Some of my seams were lifting up so I got a good heavy dose of Flex-seal on them. It rained last night and I still have a drop on the roof of the passenger side but the footwell was completely dry. I have maybe $30 and a honest half day of labor and it paid off. I still have some silicone left I can flow into the windshield but I'm pretty happy so far.

I thought I heard something... With the fan removed I could reach all the way around and down into the drain channels for any gunk.

We all know how bad the blower motor resistor area can get and here's more proof. Honestly, I should pull this out every year to check.

I really thought it was rubber, but the garage door strip worked out well and cheap. I used the old one as a guide to hold the new one up, after I smashed all the old stiff rubber off of it. $5 worth of material..

 

Install window screen under the cowl before you put it back and you wont have to worry about cleaning it any more

 

Or, don't park it under that tree anymore...

 

Looks like you cleaned out the heater box just in time or you could of had a cook out LOL
As for the seal I also used the garage door seal but I used the plastic washers that came with the seal (nails went through them) and its been held fast so far.

LOL that is what I do, don't park under trees!
Dave ----