I put one in the rear window of my 37 pickup that is 6 volts. No problem. I have no turn signals...yet. When i do add turn signals,I will probably get another light bar so I have a full lightl bar for both left or right sinal, rather than splitting one bar to flash only on one half of it.
Or, I may add two more under the tailgate as they are fairly unobtrusive and will add greater visibility.
I replaced the hydraulic brake switch at the same time as it seemed to develope a gremlin in it about the time I was adding the 3rd light.