[bbutchart63]

I'm just new on this forum and surprised no one has answered you before this.
Windshield for 64 Galaxie 2 dr fastback can be taken from the following cars:

Ford 1963 1/2 fastback and convertible.
Mercury 1963 1/2 fastback and convertible

Mercury 1964 fastback and convertible and of course 1964 Ford fastback and convertible.

All those years of hardtops take the same glass, that includes side glass and rear windows too. Convertible rear quarter glass is different from the hardtops.