Terry,
That is AWESOME!
I have been wanting to make a box scraper for some time now. I don't suppose you have any plans for a write up of how you built, or dimensions (rough or exact)?
Too bad you couldn't see the tractor side. Hard to tell for sure exactly how it works. I admit the brinly scraper blade doesn't work that well with the box pieces attached. This way seems you could really get some down pressure to use it as intended.
Just found this site. Even has plans to build a home made loader for a tractor. Sacle it down for a garden tractor. Home Made Plans The box blade plans could be modified for a box blade. Run a brace from the sides to the Briny Hitch piece for added strength.