<It would be madness to install a used windshield (even if you did succeed
in removing it from another vehicle w/out breaking it!)>

Actually, removing it from the donor vehicle is the easy part, simply cut through the old seal with a carpet knife. It's during the install that the glass is subject to stress which is likely to cause it to crack. I reinstalled one windshield in a '77, only to have it crack when I gave it a light tap to seat one corner. I have no idea how old that windshield was, may have been the original. New glass is fairly forgiving, not so when it is 20+ years old.       Jeff