how about a engine mount ... I had issue several yrs ago with
loosen side bolts on mounts,manifested as clunk in that area
when brakes applied or even in place (high rpm / low rpm).

these are easy to inspect,warm engine,lift the bonnet and dance
the pedal up and down so you can see movement of the whole engine
in my case jump was observed from left to right.

cheers
ChO

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w126 500SEC gen II euro, powered by OM617 turbo stolen from 84 300SD 2.88 diff,EGR blinded
next wish/project: w114 coupe OM603 powered