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It looks like negative are either of the small 4 bolts on the inside back plate and the center post is the positive.No, unfortunately not. The shop did the work and I had a hard time convincing them to let me take any pictures in their work area. I am sure it should be easy for you to wire them your own way.
you can see how it sags when picked up from the ends. 

wires were too long and ring terminal didn't fit
I flattened the lights by pressing back down on the ends. The flex I was talking about. 
After some time with these lights here is what I will say so far:
Connecting them together in a long line is proving to be a challenge. There is not enough support with the connecting plates they supply. They will sag and bounce around. Some sort of bracket will need to be purchased or built to mount them in that way.
I thought about that. I'm still messing with mine and trying different ways to get them to lay straight and mount solid. I'll repost once I find a good solution.I wonder if a long piece of angled aluminum on the bottom would suffice. Certainly not as elegant, but functional. Mine have been sitting on a shelf for a bit after I changed my bumper, time to add them back in.