I finally got my hands on the ribcage, a dragoon sentry dropped it for me, he was beside a road which is not far from the funeral pyre, he was found with other skeletons, usually you will find two sentries and two patrolmen.
I only handed the quest in when I had all five bones.
At level 27 I was rewarded 33% in my achievement points and 8% in my adventure points. (I was level 30 at the time, but I mentored down to 27)
Edited, Oct 12th 2007 8:25am by FinalHolmes