Date registered: Mar 2017
Vehicle: 1984 380SL
Location: North America
Mentioned: 6 Post(s)
Quoted: 575 Post(s)
I'd check... everywhere :P
If it's a US model, check behind the battery tray, under the HVAC cowl vents, interior floor panels, rear wheel arches, jack holes, and remove body panels to check inner fenders.
If it's a grey market import, there can be even crazier places to check.
Others will chime in on some specifics.
On an unrelated note, my first Benz spent its entire life in the North East. Surprisingly, many components such as the vacuum pods, door seals, dash, and other rubbery bits were great! Just the body started to rust apart.
So I got a California car for my r107 experience. Turns out, zero rust! Just every rubber components has completely dry rotted out and the dash looks like crap.
Pick your poison. :/