Tim,
From memory, the euro light has a 6-prong connector (male), of which 5 of the connectors are used. The sidelight has 2 male prongs. The following process can be used so that you don't cut any wires and can return the set-up back to the original if desired.
You will need the following materials:
-Bullet electrical connectors, one male and two female.
-Two 1-foot long lengths of 14 gauge wire.
-One circle eyelet electrical connector.
One male and one female bullet connector is connected to one wire
One female and one circle eyelet connector is connected to the other wire.
For the wire that now has one male and one female end, the male connector is inserted into the 6th hole of the 6 prong euro light harness so that there are now 6 male connectors form the euro light harness. The female end of the wire is connected to one of the two male connectors of the sidelight (does not matter which).
Now connect the 6 prong female harness to the euro light harness that now has 6 male connectors.
For the 2nd wire that has the 2nd female connector and a circle eyelet connector, the female end of this wire is attached to the other male prong of the 2-prong (male) side light wire. The other end of this wire is grounded to the bottom of the light bucket with a sheet metal screw through the eyelet.
Note that the old female sidelight harness is no longer used.
There is a way to actually make the connections so that your sidelight is activated with the blinkers. This would make a nice safety enhancement, but you will need to do some testing to see which of the wires from the euro light harness relates to the blinker.
The following post from the old Yahoo site gives the NAPA part number for the bullet connector (NAPA sells 0.176" diameter female snaps-PN 784463) and adds a bit of additional color.
http://autos.groups.yahoo.com/group/W113/message/4185Best,
Tom
1971 280sl Tunis Beige Metallic (restored & enhanced)
1971 280sl Tobacco Brown (low mileage stock)
1970 280sl Deep Red (Project Car)