Front and rear screens are absolutely the same ones throughout the production period, allowing for the tinted "sundym" glass as an optional extra, and off course the heated or non heated rear screen, and the different types of heated rear screens. However, everything is interchangeable.
There are some differences in the quarterlights that might puzzle you.
The opening mechanism of the from quarterlights is different between the series 1 and 2 cars. They are interchangeable only as complete window frames along with the associated mechanisms, not as glass.
Also the rear quarterlights could normally be opened, with the exception of the 1969 - 1970 cars, that were fixed. Again, the complete window frame is interchangeable, but not the glass.
Finally, early doors, until about 1965-66 if i remember correctly, are slightly different again from the later ones, as they don't have an additional safety pin (in search for a better description) below the latch.
