IRS adjustable spring plates

[Bruce2]

Most guys I know who have installed those SPs will use only 2 bolts. Then they get the wheel alignment done. Once the alignment is done, drill a round hole in the SP for the third forward hole. This gives you the clamping needed, and provides a way to preserve the wheel alignment if you need to take things apart.
If you leave it with only 2 bolts, the TA will move. Two bolts are not enough.