I have a '97 3500. I can't figure out where the water is coming from. I replaced the windshield and resealed the cab marker lights and neither one has helped. Anyone have any ideas where the water could be coming from.

 

Possibly the center mounted high brake light housing. Mine had water on the floor boards after a rain when I first got the truck. Took that light fixture off, sealed it with RTV silicone, replaced it and haven't had any issues since.

 

My 94 did the same thing, and the solution was the same. The gasket wasn't well planned out for the high mount brake light.

 

If you are running your AC make sure it isnt coming from the condensate drain.

Some have had to extend the hose coming out of the cab and point it down.

 

This is what I had to do and haven't had a problem since.

 

If it is a club cab, check the rear side windows. Mine is leaking and it runs down behind plastic trim, down a little depression beside rear floorboard and into front floorboard. The only way I found was I saw a drop of water coming out of speakergrill one day when it was pouring down.