Found this on S&F, this is the first V6 mercury ever built , designed by Jerry Hale for Brunswick company.
Here is the patent link:
You can see Jerry Hale now in retirement, very busy with another RC plane engine project:
the first V6 was called old blue by the conceptors, here are the pictures, and the first note by where all the V6 story started.
You can follow the discussion on this link: