Is there any way I can stop water from leaking through the air vents behinh the hood of my 1970 Dodge Dart Swinger? The water comes through the vent through the dash and floor vents all over the car.

Need some gloves and you can reach up to the 'cowl' through the vents and clean out the drain plugs on each side of the cowl. It's a 1" round hole that lets the water run out of the cowl onto the wheelwell splashsheilds.
If they become plugged up from pine needles and 'gunk' they plug up and allow water to run out the vents...

On another related note, the A-body winddheild gasket can go bad/some rust holes can let water in under the dash, along with.... Your wiper pivot seals...(that's an easy replacement for $10 worth of parts), also go bad after 10 years of use and the foam 'doughnuts' get brittle and let water run down the firewall (or drip on your right shoe)....

Good luck, and let us know how the clean up and replacment goes!

-D.Idiot