I have the euro light system on my 1980 450 SLC 5.0. My observation is that the brights and dims are seperate and are not on at the same time. While I am here do your lights have a vacume line and a "vacume motor" that adjusts the beams in some way. Mine is disconnected and I can not find any kind of a control. My beams are set to high and I am going to have to remove the light assembly and hand adjust the ratcheted reflector to fix this. Thanks Lee