I just posted an issue I'm having with upgrading a Yanmar. I bought a rebuilt 9hp to replace a 40 year old 8 hp. It was purchased from a reputable firm. I was concerned it would not fit but was assured it would. While it would fit in the engine compartment there is no way it would work without tearing out the stringers and rebuilding them. Also, the transmission and prop shaft are off by six inches. Long story short, the engine dimensions say it should fit but the configuration on the stringers and prop shaft were the issue. I hope yours is easier.