Im currently restoring my 81 280zx coupe, and ive noticed that when it rains the inside of the door seems to flood so when i drive it sounds like i have a fish tank in my car, ive aslo noticed this on several other 280zx's.
Im not sure if its the moldings on the door or the window is simply loose. Does anyone know what the problem might be.

 

It's the seal between the window and the molding on the door at the base of the window. I have the same problem. My windows don't sit flush with the molding and I get the neat water swooshing sound effects when I go around turns or over speed bumps when it rains. I drilled a couple small holes in the bottom of my door and put some rubber stoppers in them. Then after it rains, I just pull the stoppers and let the doors drain. I can only find the molding new for 2+2's and I drive a coupe. I've also got leaky Ttops, so my seats get wet too. My doesn't like the rain

 

i dunno my doors came with slits at the bottom so it drains it out...

 

i had the same problem but but icice9 showed me how to adjust the windows. there are 4, i believe adjusting nuts that you can either tighten or losen and then secure to bring the window out or in more to line up with the molding. im sure he can be more specific, i dotn remember everything btu thats kinda close to whats requierd to adjust it

 

The drain slits could just be clogged. Clean em out and see if it still pools up. Thank god summer's here though!