Nice pics there m7040. Now I can finally see what all your nice toys look like. That 4-in-1 bucket is really sweet! I can think of many uses for one of those. I could even use it to come down on fencing and yank it straight out of the ground. That would be too sweet.
One question though, why did you post that thread in John Deere Owning/Operating and link to it from Kubota Owning/Operating??
If you took a few cubic cm of that sand and weighed it and knew the dimensions of the box it would be very easy to calculate the weight. Probably wouldn't even need the forum engineers; I bet I could even do it! If you really wanted to get crazy you could fill it with lead shot. But gotta watch the lead poisoning. Maybe steel shot would be a better idea.
Yuo won't have a problem with your 4 bottom plow as I pull a 3 bottom with my m 5700 with no problem at all.I have to use 4wd at times if the soil is a little wet as I have r4 tires on mine but in 4wd it pulls very nicely.
Measured the ballast box and found it has 15 cft in it and at 150 lbs per cft that is in excess of 2000 lbs in it for rock sand. It has very good traction as it pushed over a large tree roots and all in one push and without skidding tires at all. See attached pics