Just purchased a 3500 srw with a cummins and just realized it does not have a brake controller. I cant believe ram would have a 1 ton truck that's made to tow and not make it standard. Now to my question, should I go with a factory installment or aftermarket? I'm assuming the factory installment is just that and it mounts where the controller does when it equipped with one in center dash. Also does this mean my truck does not have the heavy duty cooling system? Thanks