PPG & Pilkington are the 2 largest glass makers I know of. Of those 2, the Pilkington stuff MAY be thinner; but we had the occasional fit problems with their stuff when I was in the collision repair business, usually external dimensions.
The light stuff is a polycarbonate aftermarket deal, last I checked it was over $500 for a Duster windshield, but they were really nice and quite light. Can't recall the name, though.