Be certain which direction your PTO rotates.
Some Kubota PTOs rotate 'backwards' compared to most tractors--and I'm not familiar with your particular model.
If your rear (not midmount) PTO shaft rotates 'clockwise' as viewed from behind the machine, then Mr. Todd's advice holds: any model any make should work with your machine.
Shortening the driveshaft isn't that big a deal if you're willing to cut a perfectly good shaft. A plain hacksaw will do the job, just slower than a reciprocating or even perhaps a jig saw (use oil while cutting). Cut in increments if you have doubts. Some use a torch but I can't recommend that unless you're a better-than-average user.
The idea is to not have the telescoping shaft segments 'bottom out' when fully raised---operate the 3-point slowly and carefully until you KNOW the shaft is the right length. The biggest problem may be getting the protective shroud off the shaft so you can see how it all works and get to the shaft itself.
When you reassemble the cut shaft parts be sure to oil / grease so everything moves easily. You may need to file or grind burrs off the cut end.
And be sure your U-joint on the shaft tractor end is 'in time' or 'in phase' with the U-joint on the shredder so nothing binds in use. Before disassembly (pulling the two shaft halves apart--they just slip together) make a mark (dimple with a punch or make a shallow notch (actually just a score-mark) with the saw (above the expected cut)).
If you have or can borrow a metal cut-off saw ('chop saw') the cut will take about a minute. Wear earmuffs and safety glasses.
When using the shredder always keep in mind that the blades need to be sharp (you may need a 'bushhog wrench' to remove the blades)., the gearbox filled (some ship dry), all nuts and bolts (and 3-point lift pins) checked and tight, U-joints greased, spare shear pins (or only Grade-2 bolts) on hand or slip-clutch adjusted annually, and that blades CAN, DO, and WILL bend and break.
Please post back your experiences so we may all learn.