Joe, the glove box light wires connect at a small bakelite terminal thingy behind the glove box, on the side of the heater flap box. You can see it with the glove box removed, or with the underdash closing panel removed. The terminal has two screws, and there should be two wires with terminal eyes attached to the terminal thing. I am not sure of the polarity, but it seems to not matter. The screws are hard to see if you look in through the glove box hole, because the bakelite terminal hides them from that direction, but they are easily visible if you can look from the side (mirror helps).
George Davis
'69 280 SL Euro manual