67 Dart Conv. - No Tail Lights, Park Lights, Flashers

Too much going on here.

You need a wiring diagram.

Mymopar.com

classiccarwiring.com

Then you need to understand that the power for the brakes and the headlights DO NOT go thru a fuse, they are hot all the time.

The instrument panel and map lights have nothing to do with the brake lights directly.

Your problem could be the turn signal switch, connector or wiring

Could be bulbs

Could be wiring

Could be grounds