Looking for instruction on how to replace rear Quarter windows on 79 stang coupe  with ones from 89 coupe  

I dont have detailed instructions, but I DO know you will need to replace all the molding on the inside for it to look right, also I believe the drip-rail is differant from the later models & would need to be changed.  

The drip rails have to be changed or clipped.  If you do not change the interior quarter panels there will be a big gap between them and the windows.  If you do change them, you will have to drill sme new holes for the screws and the seatbelts.  If you want to add the molding on the top edge of the doors to match the windows, you will have to drill holes in the doors for the retaining clips and screw, and you will have to change the rear view mirrors.  If you change the mirrors you will have to find manual units or figure out a way to wire the electrical version.