water dripping from under dash

[8287silverado]

First off, I'm new here, so I'll do a lil intro. I own an '82 LWB Silverado and just bought a '87 swb Silverado 350/TBI. I like the 73-87 chevys, I'd much rather drive one than a new truck..they're cheaper, easier to work on, and just plain look better.
My '87 has a water leak somewhere on the cab. Water is dripping from underneath the dash on both sides (it's dripping on/down the kickpanels). The windshield area is still solid, the gasket is still pliable, and the door weatherstripping is sealing off like it should. Where is my water coming from?

I'd like to fix it before it causes problems, the '87 is going to be my daily truck and everything seems in good shape right now other than that leak.

[Snuke87chevy]

If you have floor vents then they could be the culprit.

[Blazin]

Check under the valance panel some times they rust there. Do you have cab light or a visor? Water can leak in around them or the screws for a visor and run down inside the A pillar.

[8287silverado]

no visor or cab lights. Not sure if it has floor vents. No obvious signs of rust damage (it's still in the original paint), but I may have to remove the cowl panel to have a look in there..

[Silver78ado]

Do you have a headliner,if not you may have a condensation problem warm days and cold nites means water on the inside cab roof the water runs down the trim pieces past the dash on to the floor..or you mite check your heater core it could have a pinhole leak and spraying under the dash,water takes the path of least resistance..runs down wires ..duct work and out into the floor..just somthing to check..Good luck