TC cannot update his first post you only get 30 minutes from when the post was first made to edit it. As for someone stating about the wiki not stating locations, that's because the wiki took all of its information from the Brady Games Guide, which many of us have possession of. Problem with the guide is although it states where to get skins and heads from it doesn't specifically state which one, also for people out there, there are a lot more challenges than the one you've mentioned that give out skins and heads.
"So... are you satisfied now?", Zelkova______________Gamestop Manager