Any vintage AP Royal Oak collectors around?

Any vintage AP Royal Oak collectors around? I've been trying to do some research on them but i can't seem to find much, i noticed they don't have the T SWISS MADE T for their tritium dials, is that correct? also they seem to have an engraving on the caseback "No. XXX" what does that mean? from what i see it's a production number? thank you to those who could chip in in advance!

Joseph