Are you talking about the Ball and Socket upper mount?
It goes together like this:
The hole in the subframe must be drilled out to 0.75" so the delrin ball can go through the frame (I use a Unibit).
The ID of the delrin ball is larger than the OD of the shock shaft so the shaft can articulate. If the delrin ID matched the shaft OD the shaft would not be allowed to move and would then break.