According to my Hollander interchange:
Windshield 67-9 hdt same, 67-9 conv same,
67-9 hdt back glass same,
Door glass regardless hdt or conv are same for 67 only , 68-9 same for hdt & conv,
1/4 glass 67 unique to 67, different hdt from conv
1/4 glass for 68-9 are same (interchange) for hdt., same for 68-9 1/4 glass for conv which interchange. But hdt is different from conv. ( as seen above) hdt= hardtop coupe. Conv = convertible
Not sure why or what on a 67 1/4 glass, irrespective of hdt or conv, is different from 68-9