I purchased a new tail light for the car. It's pretty nice and costs about $40. All the vendors sell this one. Made a bracket to attach it.

When I connected a battery to see which wire was the brake and which was the tail light, it would not work. The bulb was fine. Turns out that the mounting bolt is crimped to the light housing and this was loose enough so that the ground return would not make connection. Tightening the mounting bolt would not improve it.

I had to spot weld it in place to make it work and to make the lamp stable, otherwise it would rattle around on the mounting bolt. Messed up the powder coating a bit. I'll put some paint over it. Kind of a cheap design for a rather nice looking lamp. Mike

I hope it works for you because it does look nice and authentic.

Powder coating is tough and often thick and if care is not taken there are lots of electrical things that won't work because of a bad ground. I make repro horns and the ground for the horn motor must be passed from the internal parts to the metal flange portion of the horn which in turn is riveted to the horn bracket which is then mounted to the motor. We supply the installer with 2 large internal tooth lockwashers to allow the mounting bolt heads to bite through any coating between the horn bracket and motor but we also have 3 internal tooth lockwashers that bite into the horn bracket where it is riveted to the horn housing flange and internally additional lockwashers are used to bond the various metal parts together electrically. It is well grounded but it would appear the maker of your light was long on metal fabrication background but short on electrical background. This is a common problem on electrical items unfortunately. The washers need to be installed between various parts BEFORE the powder coating step so there is good electrical contact between things. Scraping off the coating later allows a place for rust to start doing its ugly thing.