Looking for maybe someone with similar experience. In the early 90's i had a 78' Monte, Car had a very loud "squeak" from the upper dash or windshield area. I could never find the issue, however, i had to replace a cracked windshield and it solved the noise. Wrecked the car....Today, I also have a 78' Monte and have the same exact noise. I pulled the 78' dash out and installed a 86' SS dash, so i think it's unlikely some sort of loose dash issue. It's much worse in the cold, almost gone on hot sunny days in the summer. Its very loud, even the smallest bump in the road is very loud. I have done a lot of work on this car and it's very frustrating to not be sure what it is. Two 78, both with the same noise. Any other g body cars have this and has anyone ever had this and solved it? Any help would be greatly appreciated.