The only thing that matters is that the six (actually five: pin one is unused) holes in the socket match up with the prongs on the headlight. The metal inserts (I guess they are aluminum, as a magnet will not pick them up) fit into the bakelight socket and if they are too loose to fit the pins, you could squeeze them ever so slightly, or perhaps put a dribble of solder on the headlight plug.

Mine seemed sort of lose, but they fit fine, without too much or too little resistence. I think this may have to do with the spacing of the pins on the headlight.

You will save some time and aggravation if you put the wires into the socket BEFORE you indtall the headlights, because the wires are barely long enough and one tends to pop out before you can the plug the others in, especially when there is some tension caused by stretching the harness around the headlight module.

The left side is easier to do than the right side, because there is more space to work in.

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Semibodacious Transmogrifications a Specialty

1990 300D 2.5 Turbo sedan 171K (Rudolf)
1985 300D Turbo TD Wagon 219K (Remuda)

"Time flies like and arrow, yet fruit flies like a banana"
---Marx (Groucho)