Which is why I asked, I wouldnt want to send a useless part.

The A15 will need a 3.545 for my teeny wheel diameter and 3 speed auto.
Already the a12 with 4 speed and 3.9 is marginal in revs at 100kml/hr
the economy is better than the as new A10 with 4.11 in it.
The a15 with 82mm stroke will need the 3.545 (a10 > a12 +11mm stroke)
(a12 > a15 + 12mm stroke) a10 > a15 +23mm longer stroke!