w108,107 Parts Hoarder
Date registered: Jun 2010
Vehicle: slc5.0cab 280sl5sp 280se4.5 500sl92 GONE:280sl79 4xW114/5 3x450sl72-3 280slc4sp81 280s69 73,81SLCs
Location: Philadelphia Area
Mentioned: 27 Post(s)
Quoted: 1573 Post(s)
Spot welds? Those circles look a lot more like the holes that are used to treat the inside of the rockers after assembly. Welds are extremely susceptible to rot if not protected really well from moisture. Rockers need to be welded together, and the weld spots inside a rocker panel (that might capture moisture) are very susceptible to rot. So I think MB in the period of this model would spray wax oil into the interior of the rockers to protect them from rust.
That's what I think those circles are.
My dream car is a classic sporty five speed (stick+overdrive) convertible that seats five. If, you want 70's-80's Mercedes tuner wheels, let me know.