I have been away but some data is on Timpoo's thread List of Confirmed Australian Orders.
It seems that in October Heosat, Mscoooper, Higgy, Dborn, TesAus and DavidRM (me) entered upgraded model production on the 8th and 9th, with others following in the next few days. For the Autopilot models, Higgy, LGGD and I were first in Transit on Oct 14 so that would indicate they were built the same day. Mine definitely has the short rear headrest, so I would expect Higgy, and LGGD would also. But Melocomm, MangroveMike, Timpoo and danielp have a later 'In Production' date date (after 30 Oct) than the others, and so they may share the higher headrests.