Its a 50, no venti-pane windows. When I crack the center cowl vent, the cab fills with water. I will try the Rain-X on the inside and on the outside and see what happens.
Carl
Sorry Carl,I assumed yours was a '52 going by your handle.
Even dropping the door glass a 1/2" or so should help.
Like Cletis mentions,make sure you get the right Rain-X.
The main aim is to get a high air circulation/exchange in the cab.
Have your rear cab corners been replaced at some time and if so do they have the drain/vent slots?
Replacement corner panels do not have them and they were put there by Chevy for a reason.
"The cab that
breathes"..remember?

Excessive fogging can be more often traced to water leaks though,as a glass guy i'm bordering on obsessive about them.
Getting your cab as watertight as possible will obviously help a bunch but having experienced the high humidity levels in Va. in the summer firsthand I can also see why it can get steamy in there!
A/C helps greatly in de-humidifying the air too.