Pretty easy actually. I helped a friend of mine replace his lower control arms on his 850 Turbo.

Jack the car up and support it with stands.
Remove the bolt at the bottom of the strut. It secures the ball jount to the strut.
You may have to pound on the control arm to get it out or lever it out.
Unbolt the arms from the chassis.
Replace the arms.

Do one side at a time.
The advantage is that you also get new bushings.
Can the old ones be recycles?

You might want to spray your CV boots with silicone spray, rack boots and tie rod ends as well.
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Warren Bain - '86 744Ti M46 >290Kmi, '99 V70Glt > 45K mi, '96 965 >100Kmi Wifemobile near Manassas Va.. Check the 700/900 FAQ via the 'features' pull down menu.