an update for anyone whos interested.
the friction plates arrived today. the final plate is half a millimetre thicker than the rest, 3.5 as opposed to 3.0 mm. it also has one of its tangs marked with dark ink on the outer edge. i cant see any difference in the plate where the mark is, but i will line it up with the marks on the basket, just to be safe.
im guessing the plates have had an update since the bike came out, because all the old friction plates that i took out, were the same thickness.