D cat issues
DSA,
I think you are stuck. My understanding is that it has to be an ASL 'rated examiner'. GG is the best one you can probably get in this regard, he now operates from one of the Tauranga flight schools I understand. Another good examiner would be PO from the Wellington region. I have rarely seen such a relaxed examiner/instructor anywhere although my view is that he knows which way is up despite his relaxed appearance.
As far as I know all initial ratings of 'importance' go through the ASL office. I had a friend do a D cat some years back now and he reckoned it was a bit of a joke. The examiner got 'current' but he gained his D cat which I guess was the objective and everyone left happy.
I trust you are not a current C cat or a C cat with the hour requirement for a D cat (rules a little hazy in my memory!). I also see (have observed) that with the right minimums (including C or B cat) you can gain a D cat without test, only a logbook assesment from the gnomes in Wellington.....
To answer your original question there seems to be a distinction between GA examiner (regular A cat) and ASL initial issue examiner (also A cat)...but different sign off.
RPP