Windshield is too small

Ok I’ve installed several windshields & a few back windows on various MOPARS. Removed a good one from a parts car & installed in in the car I’m fixing so I’m not new at this. Now I have the green 66 Barracuda I’m fixing. I have this old rusty 64 Barracuda I’m using for parts. Today I tried to fit the 64 glass to my 66. I was just going to duct tape it in as I have a new glass I will install after paint. I just want to cover the opening. Well to my surprise it’s too small. What gives. I took the glass out of both cars. The 66 glass was busted from a tree limb.