ok...I don't normally post to thottbot...but this quest demanded it!  From what I could see  the felboars at 33,38 area did NOT drop the glands.  Now maybe I had a HUGELY bad string of luck...but I killed at least 15 w out a drop.  Now the other Felboars...like there are a lot at 60,45...dropped at the 1/3 ratio like someone else noted.