I picked up a nice box blade when I was out in eastern Oklahoma at an auction. Never weighed it, but it was heavy enough. I put it behind a 30 horsepower tractor and all was well. I sold that one and bought a 70 horsepower tractor. It would cut and grade like there was no tomorrow, but the tractor just had too much horsepower and traction, and ended up ripping the box blade to pieces. I ripped the lower links right off it when i caught an in-movable object. Repaired them with a weld, did it again. Added about 3 times the metal to the arms and that allowed them to hold up enough to stop the tractor when hitting an something strong. (I am talking about a 6 inch piece of buried cast iron pipe about 7 feet long)
Weight versus strength versus horsepower all have to be considered...
David from jax
Oh, I don't use it anymore...