1971 Dart windshield leaking

Make sure the leak is from water passing around glass and not from rubber gasket poorly mounted to body, cowl leaks, or wiper seal problems. When water is sprayed on outside of windshield and it quickly wicks to the inside of windshield between glass and gasket forming puddles on dash, the following will fix this problem:

3M makes a black glass sealant to be used to bed glass in rubber gaskets. It remains supple for life, and will seal glass to rubber gasket, but allows glass to move in rubber gasket. My Dart had this problem, the 3M stuff works, but it is expensive at about 25 bucks a tube. A local hot rod builder recommended a glass shop he uses, I drove the car over for them to look over the job, and they took care of it in about an hour for fifty bucks total. I never got my hands dirty, and no more tidal pool formations on my dash if someone spits on the sidewalk within a mile of the car... LOL