The picture you show is a shank for a cultivator not your box blade. If he does not have the right ones those will cost you another 40 or so bucks a piece.
Yeah, those will definitely not work on that box blade.... they should look like this:
https://www.agrisupply.com/images/xxl/105648.jpg?v=20201121192603
Or....
https://www.agrisupply.com/images/xxl/72382.jpg?v=20201121192827
its pretty beefy... i used the tractor to lift it out of the trailer.