I don't know, I was at an ANZAC parade one year and the Navy officer MC talked about the Medical Corps and pronounced the P and the S.
Back on topic...
I had moved into a new set of flats and went to introduce myself to one of my neighbors. The fact I was going into the Army came up in the conversation, and he quickly told me he had been Special Forces in VN. I asked him what his MOS had been....genuinely interested in what his specialty had been and expecting some version of the old coding system.
You guessed it he was a 19-Delta. Didn't you know that for a while each ODA had a Cav Scout Slot.

I think that was back in ’51 wasn’t it!
The same guy later stole my "Go Army" bag with all my Army documentation and passports etc. Turns out he was on parole.
S