My father just bought two cars, a 1964 and a 1965 Plymouth Barracuda.
the '64 has some major rust in the frame, and the '65 is just a frame. are these two frames the same, or did they change between years? i thought instead of having too somehow repair the frame of the '64, that we could use the '65 frame. . but i dont know how that would work either. . .

Both cars are unibody. The body and frame can't be separated. That being said, the '64 and '65 Barracudas share the same Dimensions.