all Chipmunks owners in Aus should have purchased an Approved Flight Manual for each Chipmunk T Mk 10 from de Havilland Support Ltd.
Is it as cut and dried as that? Until fairly recently DHSL only provided AFM's for the Mk.22 (a "civilianized" T.10) or the Mk.21 (built from the ground up as a civil Chipmunk). They didn't/couldn't provide a T.10 AFM since there are no T.10's on the UK Register (they all have to be "converted" to a Mk.22). Given the impending CASA requirement and the then absence of a T.10 manual, my Chipmunk was registered in 2000 as a Mk.22 (the path of least resistance).
Unlike the UK, CASA accept T.10's on the register here. The majority of Chipmunks here are in fact T.10's, off the top of my head I'm not sure where the T.10 AFM's come from.