I have a 77 F150 styleside which is bombproof, except every time it rains my cab floor gets wet. my floor pans are rusting. the leaks appear to be somewhere in the cowl, but there is NO access! whats the trick to drying up this problem?

 

Don't remember any certain areas of concern, remove the windshield and cowl. Caulk all joints and seams, reinstall WS with new gasket. Believe any auto glass shop can get the seal and should R & R for minimal money.