Need help with headlights and tail lights not working 0n 61

[Apache809]

Hello, been trying to get my headlights and tail/brake lights working with no luck. Im no car electrician but know some basics of electricity. Starting from the rear I changed the bulbs and got nothing. I then tested for current with my tester and got nothing thru the wires either. Checked the fuse and it was good. Tested applying brakes and nothing either. No luck with headlights either. Only light working on it is the cab light.

Any ideas before I have to go buy a complete harness?