To find it, you'll likely need to:
1. Consult a 1970 Ford Mustang Grande wiring diagram: This will show the exact location and identify the unit itself. You can often find these online through Mustang parts websites or forums dedicated to classic car restoration.
2. Remove any panels or covers on the driver's side of the dashboard: Look for screws or clips holding these in place. Be careful not to damage any wiring or trim.
3. Carefully inspect the area around the fuse box and steering column: The flasher unit is usually a relatively small rectangular unit.
If you're not comfortable working on your car's electrical system, it's best to take it to a mechanic specializing in classic cars. They will have the experience and tools to locate and diagnose the problem accurately.