The FSM also shows the wire size in mm on all the electrical drawings. Most wiring is going to be .75, 1.0, or 1.5mm There are online charts that will convert the mm cross section to AWG for purchasing replacement wiring.

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Current stable:
1995 E320 149K (Nancy)
1983 500SL 120K (SLoL)

Black Sheep:
1985 524TD 167K (TotalDumpster™)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)