[fanaudical]

I have Boxster seats in my '75 911. Boxter seat rail modification is exactly like 964TargaC2 describes above. Here are a couple relevant threads:

http://forums.pelicanparts.com/porsche-911-technical-forum/451707-how-install-boxster-seats-74-911-using-original-sliders.html

http://forums.pelicanparts.com/porsche-911-technical-forum/220099-boxster-seats-82sc.html

The seat bottoms do become higher than the stock seats.