Are all Duster windshield gaskets the same ?

No, rear clips are 6002615, and the screws are 6002271. They also state that they are for the upper and side. No listing for anything on the bottom. The quantity says AR (As Required). It's interesting to note that they list 12 uppers and 8 lowers for the 4dr. Probably fairly close to what the fastbacks have, but, I would just count yours when ordering.