I went to tire stores and bought all their old used wheel weights. They usually throw them out, or sell them for like $10 for 5 gallon pail full.
Then I smelted them all down, and scooped the steel clips out of the liquid lead. then i poured the liquid lead into old cake pans and made several thicknesses. I then weighed them all, and stamped their weights on each one with a chisel!
It was some messing around, but I can remove all the lead in 1 minute if I needed to empty the ballast box for any reason. I can also add and subtract weight according to the weight of the loader work I am doing. the tractor handles better with less weight in the box, so its nice to add and subtract weight as needed.