'64 and '65 will not interchange for the dash unit or the tank unit.
If you have a '64 dash unit, it must be used with a '64 tank unit. The same goes for the '65 setup.
The two years have separate part #'s for each piece. They do not crossover. So in short, can NOT mix and match.
The tank does have the same part# for both years.
Loren