As this drop is used for two different final stages of the newbie armor quests... be prepared to kill a bunch of halflings. I cycled the leatherfoot camp at the stones in Nektulos over 10 times to get one clavicle. I had duplicates of every other variety of bone aside from the ribcage (only saw one).
On the bright side, I did get my drop... so don't lose hope if you are going for this.