All C-6s for FEs from 66 to 76 will fit but avoid the 67 to 72 truck trans as they are a short shaft and are not made for slip yokes for the drive shaft,I think the 73 to 76 trucks have the slip yokes and 67 to 70 galaxies will work. Since you have a 63 motor and since C-6s are newer then 65 when the starter design was changed will need the 65 and up starter and flywheel. Jeff