Connectors for W126 turn signal
 

I had a nasty accident that destroyed my passenger side headlight. The wiring from the vehicle was salvaged except that the turn signal connectors are no longer in their plastic housing, but are just 3 bare circular metal connectors with Brown, Red, and Green wires.

This is the turn signal connector receptor.
http://www.solotraveller.com/images/tn_100_0559.JPG
Which wires go to 1, 2, and 3?

Thanks!
Pete

The brown wire on Mercedes vehicles is almost always ground. Check the plug/wires on the driver side light, as they will be the mirror opposite. The red and green are likely park and turn on the right side (guessing a double filament bulb?). Just try them on the socket prongs to see which is which.

Turn signal wiring
 

The driver side wiring is inside its original black plastic square, so I can't get at its wiring. Assuming there won't be a problem of shorting things out, I'll just use trial and error.
To help save me time, which is ground in the photo?

If you look closely, there should be a cap that can be pryed off the plug (which I assume is the black plastic square) and you'll see which wire goes to which of the 3 female 'tubes' that fit the posts in your picture.

W126 Turn signal connectors
 

I will try to gently pry the driver side cover off, but don't want to break anything since it's so old. Not good if I were to lose both turn signals :-( Hopefully there are exposed wire colors to be seen.