find out the differences in the way they are wired... if they are very different... just make 2 separate ballasts. if there is only one component that is different between the two, wire both components in as the wiring diagram says... and put a switch between them so only one component operates at a time. I really think youd be better off just building one of each... especially if youre talking about those ballast kits that are about 30 bucks. if thats what youre talking about then for sure get one of each