I have killed over 40 of these at China: Western Prairie 1 and the most it has ever dropped is a bag of mesos. I understand that no equips or use items drop because the hidden-street site says it doesn't drop anything, but on this server I'd expect some nx to drop at the very least. As for the monster card, I don't know if I'm just unlucky but 40+ times seems a bit much for bosses, which have a higher monster card drop rate than regular monsters.
The only Giant Centipede that drops monster card/NX is the one that is available in the hidden map after the jq thing after you complete the relevant quests. Pretty sure you are just killing the wrong mob.
