I have a 71 el camino. I haven't driven the car at night in a long time because of head light problems. If I turn on the lights only the marker lights turn on, however if I hit the highbeam switch the high beams work. driving with high beams on really pisses people off.

GM high-beam switches are notorious for this. It's the first place that I would look.

Yeah, SS is right. I had the same problem not only in my 67 ELKY, but my 83 944. Have the switch replaced.