its not at 51,55 its like at 46,36

both sets are correct just outside the cave i noticed the coordinates were 46,35 and inside they switced to the other set mentioned above

Right think we have established where WC is and that theres elites inside but where do you get the wailing essence from?

i think ithis is part of a chain so what are the other quests

I either had bad timing or am on a busy server but the area outside the instance was over run with other players and nothing to kill out there. I remebered a trick that my guild would do farming in Dire Maul. So I went inside the instance and killed one 19+ Deviate Ravager. The next mob after that is one 18+ Evolving Ectoplasm :) Stay to the left. Don't need to jump down. If you see two more Ravagers first, wait outside of thier agro. The Ectoplasm is a patrol and will come to you in less than 30 seconds. You can pull it without pulling the two Ravagers easily. After you kill the Ectoplasm, loot, leave the two Ravagers alone, run out and reset the instance. Rinse & Repeat as needed :) I got the last 5 Wailing Essence I needed with only 5 Ectoplasm kills (100% drop rate) and 20 minutes. As an added bonus, I got a Shadowgom and 3 green armor drops from inside the instance. Everytime it was the same 2 mobs with the same exact pulls. Very easy for me, doing this one late, as a 24 Shaman.

Can this quest be finished by killing the mobs outside the Wailing Caverns instance?

Both Alliance and Horde characters can do this quest.

I never heard of it because i never did Raptor Horns. But now i know and i want that 10s because i need money. And very nice quest while doing WC.
WC wont waste your time! unless your above 29