HELP!! Strange Light Issue

[90 Runner]

So i was out driving tonight in my 1990 4Runner when i noticed that my Rear Passenger side Brake light wasn't Working. No Problem just a burnt out light.

This is when things start to get strange. My Passenger side Brake light isn't working but the Running light is, so no quick fix.

After so light testing it turns out my drivers side Running light is out but the Brake still works.

Has anyone had a similar problem and knows a problem spot on the truck or do i need to start tracing wires back.

Thanks for any advice/help in advance.
Jason

[annoyingrob]

They still might be burnt out. There's two filaments inside the bulb, sometimes only one will burn out.