Don't the Euros already have an H4 plug built into them? Mine had an internal harness that went from the H4 connector to a pass-thru recepticle on the back of the light shell.
2003 Firemist Red/grey leather SL 500
2015 Palladium Silver/black mbtex GLK 350
1987 Smoke Silver/burgundy mbtex 300E Sportline (SOLD)
Click to see 87 300E