yes you can actually get a Aust made skyline:
http://en.wikipedia.org/wiki/Automotive_industry_in_Australia#Nissan_Australia
but ADM does mean Australia domestic Market, so cars made for sale by a manufacturer sold direct in that area, no specifications on where they were build.
thus there ADM and JDM S15's both build and brought in from japan just some grey import and some ADM as sold by nissan.