Just killed over 60 Ulthorks in EW (more than a lvl hunting duo) without a single tusk drop.
I remember the rarity being similar to left goblin ears on live. On Allakhazam around the same time period the drop rate sounds like it should be ~1/10 which feels right to me as well (one person cites logs with drop rate of 8%).
http://everquest.allakhazam.com/db/item.html?item=4206
Maybe I was just on the wrong side of the RNG but figured I'd comment.