Leak under dash

[clemsonteg]

I have noticed a few times in the rain that I appear to have a leak under the dash on the driver side. I believe it may be coming through the windshield gasket, but I'm not sure. I noticed a small weep hole in the dash and the water looks like it may be coming in through the seam to the left of it. I looked under the cowl and all over the gasket and couldn't find any obvious holes on the outside. My only though was that it is somehow getting behind the gasket and I am guessing that the windshield frame is welded together and the water is finding its way through a seam once it gets behind the gasket.

I will have to have the windshield replaced when I have the truck painted due to a crack.I am trying to find out where the leak is so that I make sure it is sealed before all that happens. Has anyone else experienced this before?