So, after calling around I found that Lonestar Weights has weights that look just like the OEM kubota weights but are 60#ea and they are $418 for 3 sets shipped to KY (360#). That's without mounting bolts, he said i could source them cheaper.
My dealer quoted me $492 carry out for 3 sets of OEM weights and they are 64# ea with the OEM bolt kit (384#). So for an extra $74 I'd get OEM Kubota weights, bolt kit and an extra 24#. I went with the Kubota weights.
I they made a notable difference in ride and traction, and seem to have made a good difference in side slope stability, which is why I got them to begin with.
Also, I bought a set of steel exercise weights for a project early in the year and have had a lot of them sitting around with no use. I got to thinking about weight down low on the tractor and what I could do with those to aid in that. I rarely use the drawbar on my tractor, so I used two 6" bolts I had laying around and bolted several of those weights to both ends of the drawbar hanging under the tractor. It lowered my ground clearance about 2" but added another 130# under the rear axle. May not help much but every little bit adds up. If I find the reduction in ground clearance an issue I'll pull them back off.
Together the weights added another 514# to the rear.
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