You can by just the kit minus the second pump if needed and it is considerably cheaper than buying a dual cp3 kit with the additional pump. And most kits come with a duramax cp3 i believe as the top pump because they flow more than the dodge cp3 will. the nicest things about having dual cp3's over a large single is they fuel smoother so you dont have to deal with a surgy cruise control and throttle IMO. The dual fuelers honestly are the only way to go