[David Ivory]

If you take the front fender off you will find a foam part that ataches to the rear part of the fender.I am just guessing it is not there? And also guessing its job is to stop H20 from flying up in there..?
You shpuld be able to see it looking at the front fender with door open looking towards front.
Also do you have the plastic fender liners installed?

He better hope that truck is NOT like the first gen cab that cracks and lets water in and run down all over.

 

[David Ivory]

IDK,....that sounds bad!
But truly, I think he has a much lessor problem.
It is a prolly a windshield / Ac/ heater core problem.
I guess it could be marker lights up on top if he has them?

It IS bad!

 

[David Ivory]

Maybe the gutter is plugged up, and missing the foam!?

Most likely the poorly designed weak cab cracking up near the windshield corners from frame flexing.

 

[David Ivory]

View attachment 968820
What?

No water inside cab is a good thing. My 3rd gen used the same type of clam shell doors as the 2nd gens and it’s completely normal to get water in door jambs. None of that is really sealed.

For OP, I imagine water is running down upper cab seal and dripping towards the end. No problem.

Maybe needs new door seals? Door slightly needs realigned?