Example Format of the VIN for a 230 SL: 113 042 12 000123.
042 means 230 SL
The middle two numbers: "10" LHD manual transmission; "20" RHD Manual, 12 LHD Auto; 22 RHD Auto.
The example above would be LHD Auto transmission 230 SL.
The VIN is embossed in the engine compartment opposite the right fender along the flat surface just in front of the sub-frame access area. Repaint might make it hard to see the number.
Once you have the full VIN, can contact the MB Classic Center to ask for a copy of the Data Card which has detailed information about the car.
There are may be Job Number, paint codes and other numbers in various places on the car but the VIN is always in the above format.
The Technical Manual has information about the VIN number:
http://www.sl113.org/wiki/DataCard/VINRichard M, NYC