Chosen Solution
It differs on a part-to-part basis. Many replacement parts are genuine apple part numbers, however some proprietary parts (such as the clear rear cover for the iPhone 4 or custom-assembled tool kits) are either custom designed by or for iFixit specifically. As far as Apple parts are concerned, Apple genuine parts are made in China as are the vast majority of replacements for them. In some cases (tools specifically), iFixit offers an American-made alternative with extended warranties.
