I am looking for any website or store that can sell me a box or a type of wall-pak so I can
Mount ceiling fans to peaked ceilings

Thank you..

I have not seen any readi made boxes but you can build your own from 3/8" plywood fairly easily. You need to know the pitch of the ceiling, is it 12/12?

I have seen these made but do not know where they are sold. Try Google and eBay :)