This quest is not available in game.
Huntsman Leopold at Light's Hope Chapel in the Eastern Plaguelands will make a Cryptstalker Headpiece if you bring him the following: 1 Desecrated Headpiece, 15 Wartorn Chain Scraps, 4 Arcanite Bars and 2 Nexus Crystals.
I have discovered a use for the carapace of the crypt fiend. I am able to fashion an extremely light and very deadly set of armor by combining the fragments with some of the desecrated magical armors lost in Naxxramas.
Bring me the items I require and I shall fashion for you a suit of armor the likes of which has never before been seen in our world!