I went through the same list you have on my 124 and also couldn't find the fault and just gave up and lived with it, for a while anyway.

Later, my brake light started to flicker periodically so I checked the front pads and found them well beyond the half way mark. Upon replacement, I noticed the outer caliper bracket which extends outward sliding on two greased rods as the pads wear. After squeezing the caliper piston back in, used a C-clamp, and put the new pads in, and put it all back together, those rods that extended, now reset back inward, must have been rattling when they were extended outward from pad wear, because there was no more rattle after pad replacement!

The front sway bar rubber mounts can look fine, but look closely at the very tip of each end, right and left, and see how close they are to touching the wheel axle bases, if less than 1/8 inch, this will cause more of a clunk, metal-to-metel. I inserted within the rubber mounts some rubber cut from an old tire and that sound went away! BB