No Brake or Dash Lights

['68 Short Step]

everything has been working fine until a few days ago when my taillights and dash light quit working. I looked at the fuse and it was blown. Replaced the fuse and everything worked again. about 5 miles down the road the taillights and dash light quit working again. Checked the fuse and this time nothing was blown. I replaced the headlight switch and dimmer switch because they looked old and corroded. Still nothing. any advice on best place to check wiring would help. Everything seems to be connected. thanks for the info