What the tech was referring to are the brake strut mounts. They are responsible for holding the castor in spec. They will knock very loudly if faulty. Also it takes an experienced tech at least 4-5 hours to do a suspension rebuild with all of the special tools.
The work I see the most is
Tie rods, drag link, idler arm bushings, upper control arms, ball joints and brake strut mounts.
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