Depending on the kit and what headlights you have you should be able to fit everything inside the housing. If not, on the engine side of each headlight opening there is a plastic divider. There is enough room on top of that to mount the ballast. I just had to drill one hole then zip tied the ballast to it. This area seemed to give the ballast the most protection from the elements, keep it out of the way, and close to the headlights where you still have plenty of wiring available
2018 Ram 2500 6.4L Hemi Tradesman