I have a small, rain leak from this part of my 2005 truck but I cannot figure out how to access it or if it is even possible to access.

When I remove the passenger side floorboard plastic kick panel, then remove the plastic, rectangle grommet behind it, I can see up into this cavity with a small flashlight and mirror.
There is a piece of white wool-like material up at the top of the cavity, with water dripping down from it after a hard rain. I believe it is coming from a factory weld, under the hood, just to the left of where the (2) hood hinge bolts are. Placing some RTV gasket maker on this factory weld has seemed to almost stop the leaking but has not sealed it completely. It would be nice if I could access the top part of that cavity to verify that the factory weld is the culprit. Any help would be appreciated.

 

Maybe it is a windshield leak?

 

I'm with Roadie on this one... I bet it is the windshield gasket.

 

Thanks. When I recently purchased the truck, dealership installed a new, front windshield. Week later, I noticed the leak. Company that installed the windshield replaced it with no questions asked.
So when I noticed it leaking yesterday, I assumed it could no longer be caused by windshield. Though it is possible the gasket was never replaced with the windshield & that is the source of leak.
When I pour water on that weld under hood, small amount of water does make it's way down that cavity, even with the RTV gasket maker.