Here is a pic of the updated balljoint attachment
The change occured in '72 on 911s. I would want a 930 strut, as it was set up oem for Bilstein and is a straight bolt on. These struts come oem w/ HD.
I've used both setups sport all around and hd front sport rear(currebt setup) there is very little rel difference in the feel between them. Either works fine w/ the heavie t-bars.