The plugs all had the same resistor values however S and N positions differed depending upon whether it was an M102 or M103 engine and whether it was KAT or RUF (ie. with or without exhaust catalyst) meaning that different settings were needed in different applications. The owner's manuals generally only suggest operation using either the S or N settings, however if you read all the posts from the previous threads I had links to, it appears that early versions in particular did offer increasing ignition advance at higher resistance settings. My measurements revealed this not to be the case for my M102 and M103 (both 1990) where the resistance values corresponding to the S and N settings were about the only valid settings (the remainder defaulted to maximum retard).

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107.023: 350SLC, 3-speed auto, icon gold, parchment MBtex (sold 2012 after 29 years ownership).
107.026: 500SLC, 4-speed auto, thistle green, green velour.
124.090: 300TE, 4-speed auto, arctic white, cream-beige MBtex.
201.028: 190E 2.3 Sportline, 5-speed manual, arctic white, blue leather.
201.028: 190E 2.3, 4-speed auto, blue-black, grey MBtex.
201.034: 190E 2.3-16, 5-speed manual, blue-black, black leather.