Brake/Running Light/Turn Signal Problems

[LuvNLife]

1985 C10 2wd short bed, 350/350, pretty much stock and undamaged, just showing it's age.

I've got no rear lights at all - no running lights, no tail lights, no brake lights and no turn signals. Headlights and turn signals up front work fine.

My question is, could this all be fuse related? I found a simple diagram of the fuse block, and all I'm seeing is "TL CTSY" related to the rear lights. It's miserable outside right now, so I haven't pulled the fuse yet.

Thoughts and suggestions would be appreciated...