Charlie's right on the three versions. I still recommend replacing the 'kit' every two years simply because the impeller takes a set after a while, which does affect its performance. Since the Bravo pump is on the engine, replacing the kit isn't too difficult, once you master getting the hoses off and on. One trick I used is to remove the pump first and then the hoses, checking the 'bend' of the hoses to install them in the same direction and on the original fittings. On installation, put the hoses on first and then mount the pump. Hy