5-pin must use dual ballast
4-pin can use dual ballast
The difference is the 4-pin moved the step-down of the power needed to run the module inside, as it was already getting 12v also.
If you wire it for a 5 pin/dual ballast, you can run either box. i did this way back when on case I broke down and they only had the 5 pin in stock.
If you use an msd box at some point, just bypass the ballast and hook the 12 v side wire to the coil.
