FWIW, my windshield leaked at the top corner on the passenger side. I kept noticing that the carpet between the front seats was wet and staining. Because of the stain I thought it was coming through the floor, then one day I noticed that the passenger side floor mat was wet. I thought it was coming from AC condensation (clogged drain), but upon under dash inspection I noticed it was coming from the side near the kick panels. I looked up and the headliner was soaked at that corner of the windshield. I'll put sealant on it as a temporary fix (per other AstroSafari.com posts). I may get the windshield re-set. I also just had the infamous dutch door weatherstripping leak, so the carpet is currently out and drying. ('93 LT)
Edit: I taped the corner of the windshield with Gorilla Tape. After the next heavy rain the corner of the headliner got wet again, so my leak may also be coming from the roof rack (as MI_Ghost said) and running on the top of the headliner to that corner.