Is anyone using either of these water pumps? I have the 1st gen. Casco pump/w riveted impeller. I'm considering replacing it with either Casco's 2nd gen. pump/w 1-piece cast impeller or Flowkooler's pump. I don't like the thought of the riveted impeller coming apart on Casco's 1st gen. pump. I suppose that's why Casco upgraded to a 1-piece impeller.