I thought that the term "modular" refers to the ability to drop in two more cylinders, to create the v10 truck motor. In fact, I'm sure of it. But maybe the term has dual meanings.
Perhaps you should look up the definition of modular. No dual meanings here.
Parts from 1 motor can be used in another.
Example: Pull the parts from the cobra and use them in the GT.
I have no idea if the v8 can have 2 cylinders added to the block to become a 10 so I cant comment there. It would be the first time I have even heard of it being possible.
Ford's use of the term modular means the same short block but with many trim levels. Think of how many differant applications there of the 4.6L and 5.4L Modular motors...