Testy Festy (Story Mission)
After the liberation of Fall's End, talk to the cook inside the Spread Eagle to kick this one off.
Before you get started, note that the second mission in this questline has the Deputy committing some pretty horrific cruelty to animals. If that's not part of your preferred videogame experience, you might give this one a miss- there are no special bonuses or benefits to completing this quest. If you plan to go ahead with it anyway, head to the Hyde Barn, well east of town.
Talk to the owner to find out his key has been eaten by a vulture.
There are three vultures here to kill, and of course the key will always be in the third one you shoot. Sniper rifle is good bet here, or a scoped assault rifle. Remember that even bullets take time to travel, so lead your target a little bit to make the shot.
With the key in hand, enter the barn to claim your prize.
Shoot the lock off the garage door, then drive on back to town.
There are no plot specific obstacles in your way, just park in the designated spot to complete the mission.