Help identifying water leak in cab

[hey its me]

My floor gets wet on the passenger side. 81' short bed c10. Initially I thought it was water leaking past the windshield, but today I pulled the kick panel off (where that vent/flap thing is) and poured water over the windshield. I saw the drip come from inside where the kick panel is, up above. I can't really see where it is, or how to get to it. I took a few pictures. I'll upload them soon. I don't really know what to do about this one. Any help would be appreciated.

Thanks- Ian