I need to get the 40 amp kb bap for my setup because I'm maxing out my pumps. I know someone that has one for sale but he's not sure if it's the 20 amp or 40 amp. Is there a way to distinguish the two? maybe a part number somewhere? he said there's a 15 and 17 on the back of the unit but that doesn't really tell me anything. I have to imagine there's got to be a way to tell the difference. Does anyone know?