OK, hope I can make this understandable. The hydraulics to run the FEL/bucket are all rubber hoses EXCEPT out front where the hydraulics cross from one arm of the FEL to the other. The cross-over plumbing is steel tubing.
A year ago I had the Kubota dealer install a Land Pride grapple, WR Long third function valve and all the plumbing. ALL the plumbing for the grapple is rubber hose. When I dealt with the local Kubota dealer - there was never a mention of a "Kubota brand kit".
Hope this is helpful.
Correction: now that its daylight I went out and checked. The hydraulic lines to run the FEL/bucket are all steel and tightly tucked up under & inside the loader arms.