I guess I got lucky on these, it only took me about 15 kills. Anyhow, if you take the quest called Scaring Shaky from Booty Bay (don't remember exactly which NPC), you can knock out two quests at once since they both require you to hunt these gorillas. Just a hint -p.

The gorillas can be found at 32, 68

Once again, another quest with a wild drop rate. The gorillas are found east off the road coming from Booty Bay. From the tunnel leading to BB, it's maybe a 30 second run, if that. You can also find another half dozen gorillas west of the road. Good luck on this one...the place is usually camped. I have seen this quest take an hour before the sinew drops, so be prepared.

While you're there, you can triple up on quests. The gorillas drop the giblets needed to finish the quest "Scaring Shaky" in Booty Bay, and they also drop Gorilla Fangs, ten of which you'll need to start "Stranglethorn Fever". The fangs also sell well to vendors if you finish that quest (or have no interest).

39 Pieces of Heavy Leather
27 Gorilla Fangs
17 Coarse Gorilla Hair
3 Chipped Gorilla Teeth
2 Heavy Hide
4 Large Fangs
4 Medium Leather and 15 Thick Leather later....

Took about an hour and a half to get.
Got about two bars of xp at lvl 45.

I found it in the location of 34,65 near the mountain. The Gorilla ran up to me out of the blue actually. Try for any Gorilla's behind the trees near the mountain around this area.

Wish you the best of luck!

A lot of anecdotal evidence here for a higher drop-rate based on the location of where you killed the gorillas. So I guess I'll throw mine in as well, although against the case.

I just completed this quest for the second time between two of my characters. Out of those two characters I simply randomly killed the gorillas without a preference to close or far away. Out of those two times the first drop was from a kill that was one of the farthest from BB, and the second drop on my other character was from a kill around the middle of where the spawn points are. Also, taking into account others who have reported their drops with coordinates that were given at seemingly random locations and not "nearer" to BB.. I would say there is probably no correlation between the location you kill an Elder Mistvale Gorilla and when the quest item will drop.

When things like this occur people tend to report the hits and ignore the misses. Another thing is people will kill just the gorillas near BB, so when it does finally drop it seems like it is confirming the superstition. Anyway, please don't take this argument as an insult or anything. I know we're all pattern-seeking humans and we'll look for patterns even when there aren't any (I've been guilty of this myself!).