'76 Lights Don't Work Right

The turn signals and the tail lights in my '76 aren't working, but the head lights and the break lights DO work. I checked the fuses (at least what I THINK are the right fuses, the wiring in this thing isn't quite factory :banghead: ), and they're fine. I doubt all of those bulbs burned out at the same time. I was going to try replacing the mechanism for the turn signals, but then I noticed that the tail lights were out too.

Think it could be a wiring problem? Think it would be expensive?

Liz