I know Yamaha built the blocks up to 2000. Mercury started building their own for 2001 when they went to the EFI. I have a 2001 60 hp EFI that I bought new. I also have a good friend who has worked at Mercury in Fon du Lac for about 25 years. I think it was about 2008 or 2009 that Merc built the plant in China and started producing the mid size there - the whole motor not just the block. My friend now repairs those that are returned from the dealers. Full time work until he retires it appears. Some he can fix in an hour or two, some take a lot longer.