That's good to know! I just assumed that the GKN parts were OEM since the eBay listing with the GKN kits states "New Original Equipment Manufacture Parts. Not a reproduction or aftermarket", and the brand on the eBay listing is listed as "Loebro/GKN".
The only thing that concerns me about the
RockAuto kit is that the CV end cover shown in the picture looks different from the pictures I've seen of the OEM part and the pictures on the eBay listings.
Maybe RockAuto just used a generic picture of the kit not specific to the Boxster. Can you confirm what your GKN CV end cover looked like?