For the DKse tractors, those bolts are kioti part #04613-50240 and kubota part #01133-51016. The kubota bolts are easier to find online.
they are M10 x 1.25 x 16
Its the length that is difficult to find in a hardware store, and I don't feel like cutting bolts whenever I happen to loose one. Especially when they are $1.25 each from Messicks. Buy a bag of 10, use blue locktight, you'll be good to go.