I had an 82 that leaked real bad in the rain. I cleaned the drains and it still leaked. The seal was good on the windsheild. So while looking around I found that the leak was in the sheet metal around the fire wall. The leak was on both sides of the cab. So with a little hillbilly/redneck thinking, I was able to wrap some cardboard in poly sheeting. Put that under the dash over the tranny hump to a plastic pan on the pass floorboards. Then put some of that same sheeting under the dash on the drivers side so the water would drain down the floor pan and out the rotted seal at the bottom of the door. For a few months, it would rain harder under the dash than out side. I had no luck doing anything else with goops and the likes. Drove it that way for a few months till I got it out of the drive for scrap.

John