its 100%. Every single source is the same 100% they removed all randomness on legos this xpac after the first time they tryed this being so tied to rng everyone hated it.
they require layer 3 and each only drops in the correct wing. The wing changes weekly if you dint get the drop the first time clearing a layer 3 your in the wrong wing. They drop regardless of current spec or loot spec set, you just need to be the correct class.