I'm not sure if there was a Euro 1981 380SE... I only follow the American-spec models... :^)
American-spec W126's '81 through '85 used sealed beam headlights. They appear set back in the car's face.
However, a popular modification was to replace the headlight assembly with the Euro-spec one where the entire headlight assembly is flush with the face of the car (like in the '86 - '91 W126's, sans wipers - most think it looks better).
So that MAY be an indication of a Euro, but maybe not...
Anyone else have pointers on how to identify a Euro version??