69 mustang parking lights

I have a 69 mustang. The front parking lights go out when the headlights are on. just the fronts, rears are on normal. if I put the headlight switch in the parklight only position the front and rear parklights and marker lights are on also the ignition key is illuminated along with the dash lights. with the headlights on the front parks go out and the ignition illumination go out. the dashlights and rear parks remain on. I just replaced the headlight switch with a nos ford one and it is still the same. Is this normal or is it a wiring problem? Thanks Hank

Thanks alot guys. I won't be pulling out the wiring diagrams after all. This is my first classic ford I didn't know it was normal.