Yes, the top link adjustment must suit the task. That is why some guys who use the box a bunch install hydrualic toplinks so they can vary the top link length as they work. I will do this in time. Said another way, there is no one length for a top link when used on a boxblade, it must be adjusted for grading, or digging, or leveling, or smoothing and these settings vary depending also upon you are working in reverse or forward. I dig and grade forward, smooth and level and spread in reverse. It happens that with my box that the geometry is such that when it is about right for digging in forward it is pretty good for smoothing and spreading in reverse. My box is the swing back type. Learning to use the box in reverse is key. It allows you to use one setting of the top link to accomplish multiple tasks. I also use it to bulldoze in reverse such as to push up cut down brush into a pile or push out dirt I have dropped from my loader in piles.
I, not being the argumentative type, still contend that there is a "just right" size for the boxblade for each tractor and for the BX based on my experience I would not be able to get full use from something in the 400 lb range.
I, grasshopper, have mastered the box, I can say that confidently, it no longer holds any mystery. That is not rhetoric, it may be a boast but it is also fact /w3tcompact/icons/wink.gif . J