OK, just did a little digging; These are indeed US GT3 seats, also sometimes referred to as sport seats. What I am selling were standard seats for the GT3 and optional on all 996's. The seats referred to above with pass throughs for harnesses are European GT3 seats, some said only available on Euro cars, I'm not sure. Post I am referring to:
https://rennlist.com/forums/996-gt2-gt3-forum/1181360-996-gt3-seats.html