So it's been almost 1.5 years, and 15k miles I've been living with the death clunk on this car, and it's been making me crazy the entire time.

Since my last update, I replaced front springs (not broken, but figured why not?), replaced driver side ball joint (2nd time in 20K miles), and swapped front shocks side to side (to rule out a bad one). No change, the noise persisted. One interesting observation though, each time I serviced the car, and had the spring compressed, the noise would disappear for 2 days or so (about 140 miles of commuting) then reappear.

Eureka moment last weekend. I took a gearhead buddy for a spin in the car (who I have been discussing this suspension noise issue with since the beginning of this saga). He heard the noise, even felt it through the chassis, and agreed it sounded like it came from the shock itself. We popped the hood, turned the wheel to get visual access to the front suspension, then he jumped up and down on the front crossmember while I watched the suspension work. I heard a faint click/knock, pinpointed the source at the bottom shock eye, where it attaches to the lower control arm. I could see a tiny bit of slop in that joint.

That's when I connected the dots - When I installed these new shocks, for reasons I can't recall now almost 2 years later, I reused the bottom bolt instead of the new one that came with the shock kit. I only re-used the bottom bolt on the driver side, used the new one on the passenger side. I think the passenger side one was stubborn to remove and the hex head got boogered up. I supposed my thinking was "if it ain't broke, why fix it". Anyway, the bolt that came with the shock kit was just a tiny bit bigger than the old one, about 0.1mm according to my vernier caliper. Using the old bolt with the new shock obviously created a larger clearance and this was my stupid dang noise the entire time!!

Lesson learned: when they give you new hardware with a part, you use it even when the old hardware is perfectly serviceable.

The car is riding sweet, and silent. Just as a proper Benz should.

Hopefully this thread will save someone else from pulling their hair out for a year+ (haven't got much left anymore).