68 Barracuda Drivers side signal problem

Most any classic vehicle with 1157 bulbs... when the turn indicator in the dash comes on with the park lamp, the fault is lack of chassis ground at that front park lamp fixture. Why? the current uses that front turn circuit for a ground path. I've seen this condition in all sorts of vehicles.
Your front fixtures are mounted in a plastic grille so they are grounded to the core support with a wire like you headlights. Could be a loose or broken ground wire but the ground path does begin at bulb base to interior of the bulb socket. Rust in there can be the cause.