I recently replaced my old BF130s with two BF150s from a 2006 model year boat. Both motors have less than 600 hours and have ran flawless before last week. The powerhead serial number from port engine is:BANJ 1100055. Is this a 2005? I pulled the chain case and I feel this is probably where the water is coming from.. There is corrosion, rust and the gasket looks very flat..Appreciate opinions as I do not want to go further and pull head to look for gasket issues there. I ruined the chain case, can someone please tell me the correct part number as there are two numbers listed for the 2005. I also got a MIL and warning and healtech diagnostic indicated a bad 02 sensor. Are the aftermarket 02 sensors available adequate or do I have to buy the expensive honda 02 sensor for BF150s? Pat