The only way you can be 99.9% sure the parts will fit properly is to go to the dealer and buy OEM parts. The problem is you pay a premium price for this luxury!
Getting the correct parts from an aftermarket supplier can be a challenge. The obstacles can be a counter man with limited mechanical knowledge, or who just doesn't give a rip, certain parts may be slightly different due to other optional equipment on the vehicle, there may have been a mid-year change in specs, etc. And depending on how the computer program is set up some of these differences may not be broke down the same way as the dealer's listings.
Nowadays almost all aftermarket parts (except for a few premium lines) are made in somewhere outside the U.S. The part you buy at NAPA, Carquest, Autozone, online, etc might have all been made in the same factory - or not. And they all change suppliers, so the part you buy today at your favorite store may have been made in China, and if you go back next week or next year and buy the same part it may have been made in Taiwan or Mexico.
It's kind of a crapshoot so if you get a good part that fits properly at a good price count your blessings!