Thunderlord Cache
Thunderlord Cache is found at [34.2, 23.5] atop a rock outcrop at the southwestern end of Daggermaw Ravine in northwestern Frostfire Ridge, in the basilisk area. To access the cache, start at the southeastern end of the two-arched rock outcrop. There's likely a True Iron Deposit at the base. Run up the ramp, then run across the bridge to the northwest to find it. The cache contains the 
[Thunderlord Longspear] and 10-20x 
[Garrison Resources].
Don't forget the Canyon Icemother immediately below.
Tracking quest
To check whether this chest has been looted, copy and paste this command into the chat window:
/run print(C_QuestLog.IsQuestFlaggedCompleted(32803))
If a "true" appears in the chat window, this chest has been looted; "false" indicates the opposite.
Trivia
- The cache would have been an objective of
[The Frostwind Slayer].
Patch changes
Patch 6.0.2 (2014-10-14): Added.