New r6 part locations

So I assume the monster-specific rift r6 (riftshell, riftscale, etc.) will drop from riftborne monsters from either the first 4 random drops or the fifth if you break the special part, and it doesn’t drop form actual part breaks. The scarcestone will only drop from 9-10* monsters, but does it drop from the usual r6 spot (tail for tobi, head for jyura, etc)?

Feel free to tease me if this was explained in the announcements or somewhere else. I skimmed everything pretty hardcore this season.