most of the time its the rear windscreen.as its sloped,water flow down so fas thay it wont leave a trace.I used to drive 1st gen also, due to water leaking into cabin problem i sold my car. At spare tires area mostly is from the rear light, when u take out the rear light from ur body u notice there is a foam gaskets it might be harden so cant really block water from leaking in.
I face another major leaking is the water all over my cabin. i tot is my aircond water leak. Then found out is when i do the water test at my foreman workshop he use the holes to test at the car roof and funny thing is water come out from the back seat beam totally no idea how the water from top go to the bottom beam. I think might be the original body welding break or something else. so at the end sell it
most of the tine it will flow in the rubber and tmonly show when the rubber ends at the corner.