It looks like I have JUST enough room. Was wondering if anyone has done it, knows someone who did it. It's basically the same dimensions as the newer GM's right? What about my prop? I think the current 2 blade is 13x8, what should I use for an engine with double the power and a lower final drive? Final drive of the Renault is 3:1, I'm fuzzy on the Yanmar, the manual lists two, 2.83:1 and 2.14:1. Also RPM is lower, so it washes out I think.