My 88 chevy nova tail lights are out. I have replaced the bulbs and checked the fuses and they are both fine. The side reflector lights and all other lights work except the tail lights.

Check the taillight ground. Verify with a $4.00 test light.
If you don't have a Tracer/Toner, you could see which spots in the headlight switch are hot, then back feed from tail light socket and check at plug for voltage, this will tell you wireing from the back to the switch is good. You will also know which wire should be hot when headlight switch is on.