Get some one to drive the car and take a length of heater hose sticking one end in your ear and moving the open end along the glass area until you locate the whistling point.Then take some children's clay Kif you can still buy it) and build up the area behind the window seal. keep doing this procedure until all is quiet.then go back and replace the clay with a more permanent material. I use to work at a Ford dealership in So. Cal. fixing the leaks that Tim missed!
Tim do you remember the spot weld on the rear roof seam under the stainless steel trim molding on the big Country Squire Wagon ( beautiful car) that would leak water and you could hear it rushing along both sides of the headliner? That one was fun to find!