Woods makes a 65" box blade that works well with the 33. The 65" extends out past the rear tires so you could use it close to something and not worry about touching it with your tractor. This box blade can stop your tractor if you take to much of a bite when grading or trying to rip to deep. I'm sure you can use a 72 but you'll just have to watch how aggressively you use it. Also you might want to look into a hydraulic top link as this really makes the use of a box blade much easier.