My 67 has had this problem from the day I got it, When the head lights are ON and you turn the right turn signal on the signal light wont work. When the head lights are OFF and the right turn signal is on they work.
Has anybody had this problem???
All other lights on the car work correctly.
Any info will help..

Check your bulb sockets and clean the ground wire. You will get them to work properly this way.

Kev