Tail lights dont work???

My tail lights and side marker lights are not working on my 68 Dart.They worked then blew a fuse.I changed the fuse and they worked for a few hours.Then they quit again and will not work.The fuse is OK this time.The turn signals work and the head lights work.But the passenger side headlight is real dim.I dont know if there is somthing wrong with the head light but this happened when the rest of the lights quit.
I put all new fuses in the fuse box,put a different dimmer switch in because the old one was stuck on,and all the light bulbs look OK.
On a 68 Dart does the Dash bolt in under the windshield like a 68 Coronet.I am thinking of taking the dash out this winter and checking everything out Any ideas anyone thanks for the help Jim