This quest:
Heroic Deeds - Quest - World of Warcraft
Gives a cache which gives you a guaranteed 516 item.
There are two versions of the quest: Alliance and Horde.
Therefore, when you faction change, you can do the other factions quest, so you can receive the cache and get the 516 item again.
So if you have faction changed recently, go pick up your quest and get your 516 item again!