Re: Are the mounting holes a standard size?
There is a BIA standard but that doesn't mean whoever drilled em was paying attention to it. I just did what you're contemplating and found that the holes in my boat transom were off the standard by 1/2 inch. However, the shift occurred in the section that is slotted on the outboard and it just prevented me from using some of the holes for adjustment. When I bought a jackplate I had to redrill the bottom holes in the jackplate for the holes to line up with the transom holes.