Upper A-arm "Locking Plates"

[<hrgspg@dejazzd.com>]

In my anger to remove a difficult bolt securing the upper ball joint to the 
upper A-arm, I mangled one of the "locking plates" that prevents them from 
loosening. On the microfiche and the shop manual I have, I don't see them. Are 
they absolutely necessary? If so, which I'm guessing they are, are they 
available from dealers or vendors? Part number? As always, thanks in advance.