Thanks for your help everyone. I went out and got a voltage tester. Looking at the wiring diagram it looks like one of the wires from the brake light go to the headlight switch...and the other wire goes to the blinker switch. So I'm not exactly sure what to test. Will 1 of the wires going into the brake switch have power when the brake is not being pushed..and the other wire gets hot when the brake is pushed??

And about the rear end....where in the front do you put the diff fluid in? I think there's a bit of diff fluid dripping out of the rear axle...no way to fix that?

A new question....why do you all refer to the trucks as fridges? Because of the boxy shape? I'm guessing that you say orphans because these model trucks aren't as widely collected?