Take the Corroded Black Box to the Hall of Arms in Ironforge.
The surface of this metallic black box is heavily pitted, as if it had been immersed in acid - it must have been sitting in the giant condor's stomach for a long time.
Turning the box over, a symbol is found stamped on its bottom. Below the symbol are the words:
"Engine #19 - Ironforge Siege Brigade"
Also, you get: 50
Thanks for the done work!