... it's the upper shock mounts and not the shocks themselves. (item # 3)
I have over 163,000 miles on my original shocks and they still perform well, but I've had to replace both top shock mounts.
These mounts are similar to the engine mounts in that they're made from rubber which fails in time.
The metallic clanking is probably the shock shaft hitting the strut bearing because of an overly worn out upper shock mount.
To find out you must lift the end in question, remove the tire and pull on the shock shaft with your hand to see if there's any movement. If there is, you have a bad mount.
Happy Boxstering,
Pedro