1930/31 Coupe Wood Blocks

[George, Iowa]

1) Are there only 4 wood blocks per side on a 30/31 Ford Coupe? (See Pictures)

I have another large hole in frame (See blue tape sticking out of hole) and was wondering if I was missing a block?

2) Is there a book that has the dimensions of these blocks. I don't know if these blocks have become compressed down through the years.

Thanks for your expertise and experience.