Any tricks to get haze off windshield?

I was trying to find my buddy a good used windshield for his '54 Belair becuase it's got an unknown haze on it and will not come off. We've tried everything we can think of- vinegar, headlight cleaner, sanded it with fine sandpaper nothing helps. It is definatly on the outside of the glass. It helps to wet it down to see temporarily. Any ideas you guys know of would be great becuase a new windshield is $400-$500!!

 

Bon Ami or Bar Keeper's Friend usually cuts most haze for me.

 

bar keepers friend, my dad swares by the shit for almost anything. its worth a shot

 

a razor blade, laquer thinner and steel whool usually do the trick. not in the that order but it usually works.