I have been having a problem with the front directionals on my 69 SS. Specifically, my directionals and 4-ways work when the head lights and parking light are not on, when turned on the front directionals and 4-ways do not work they stay on constantly - no breaks. The rear works as it should. I have replaced the flasher, lamps in both units, and the head light switch. Using a test light I have found that from the harness GM connector, where the parking light assemblies plug into works fine on both sides. So I am thinking a ground with in the parking light assemblies themselves???