[dsraven]

I was involved in a new fire truck purchase and it was specified on every point of contact between aluminum and steel that a plastic shield be used between the parts. some of those got missed on the steel door handles that fit up to the aluminum doors and the paint was peeling off all around them due to electrolysis that started there. it doesn't matter if it is inside or outside as the metal doesn't know the difference. you have probably tried to remove a steel bolt that was installed into an aluminum housing, at some point in years past, and noticed it had "white powdery stuff" in the threads. thats the stuff that forms from electrolysis. if building it from scratch it doesn't take much extra to include some sort of deterrant. a thin sheet of plastic or rubber is all it takes. rubber would help curb any rattles that may come up.