The silver plating can turn jet black. Color means nothing. Overheated pins will have melted wire insulation on the back side, a blistered appearance, and usually melted plastic around them. You have none of these.

Alternator size doesn't matter. If the brushes are worn out on the regulator, you'll get erratic voltage from it. The dipping lights and various flaring you describe is a classic failing regulator. Fix it before you're walking.

__________________
Current stable:
1995 E320 157K (Nancy)
1983 500SL 125K (SLoL)

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

Gone and wanting to forget:
1985 524TD 167K (TotalDumpster™) [Definitely NOT a Benz]