I don't have rear lights, plate lights or rear side markers working. Have changed the fuses and bulbs with no luck. Everything else works fine. This is on an 83 camaro. Any help would be appreciated.

Thanks!!!

Sounds like you lost the ground connection to the rear lights. Start at the tailights and follow the wires. There should be a wire attached to the body somewhere with a ring terminal and a screw. Make sure it's clean and tight. If you find a connector along the way, pull it apart and check it for corrosion.