Original FMXP pumps had a slight variation to this current Suction Cover - the body O-Ring was imbedded in a channel around the cover and was a press fit inside the pump body volute (sealed on the side). That style pump face suction cover is no longer available and is replaced by this FMXP2 version. The body o-ring should also be changed. These new models have a compression seal on the body o-ring. The original pump body remains the same.