I'm not sure about the MB, but American undersized rod and main bearings are often marked on the backside of the bearing. I agree with the post earlier-if a bearing/surface got roughed up, I would definitely have the crank turned and the "big end" of the con rod checked. By the way, isn't piston clearance normally checked by using an internal micrometer on the cylinder in 3 or 4 different places and an external mike on the piston in the same way(or is the Benz different??)? I'd want to pull out all the oil gallery plugs, camshaft, and clean the daylights out of everything-I'd hate to go thru all that work and big $$$ just to suck a turbo!!!

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1982 300DT 190K (Diesel Purge + synthetic oil=smoothness at last!!!)
2004 Ford E-350 6.0 L PSD 227K
2006 Dodge Ram 3500 SRW HO Cummins 4X4 48RE 42K (brute force tow vehicle)
2005 Scion xB wife's rolling pop can
1993 GMC Sierra C3500 6.2 142K