rear lights

[slowboy]

I removed my bed on my '72 GMC to have rockers and cab corners replaced. I had 2 aftermarket brake/turn lights strapped to the rear chassis so I could drive truck. I removed aftermarket lights, put my bed back on, connected harness to rear lights. Now the only lights working are the turn signal lights. The brake, park, and backup lights don't work.

I've searched this forum but not sure what to do except make sure all lights are grounded to frame.

I don't see a black ground wire from harness. There 'is' a brown wire from harness that's sticking out by itself. I tried grounding it to frame but that didn't help. Then I saw in Haynes book that that was the wire for License plate light.

Please help...

Thanks,
Keith