65 and 64 valiant parts interchange

Why do you have to change the valve bodies i'm puttin a 65 model in my 63 and everything from the 63 everything looks the same and the cables hooked right up
I went through a lot with a cable shift in my 65 GT.... I don't think there should be any difference until 1966. 65 was last year for cable shift, no pushbutton that year.
The GT has a little console stick shift.
I THINK the National Traffic Highway Safety Association and others had decided to mandate the P-R-N-D-D2-D1 shift standard as enough accidents had occurred as a result of unintended gear selection.
65 was last flat plate output intended for ball and trunion drive shaft.
Others?