I bought a voltage booster for my 6 volt 51 Chevy 1/2 ton truck. The plan is to send 12 volts to my new LED tail/brake/turn lights (they put out very little light when the truck is idling with the headlights on. I have installed their own ground wires & checked all the wiring. Evidently these lights just need more than 6 volts). How can I wire it up so only these lights get the 12 volts? It's OK if the front parking lights get 12 volts too.

My dad always told me, "Don't force it, get a bigger hammer".