Learned a New Brake Term Today

I'm 99% percent sure they were factory installed.

Update to post #11: After comparing the front 10" backing plate and the rear 9" backing plate, I find the 9" anchor pin is perhaps not machined for the anchor pin plate. The 10" has its own little relief step for the plate (photo #1) and the 9" does not have the same relief (photo #2).

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