Lots of good information to be found on search.
As to at least the hydraulic filter, it has been determined so far that NONE of the aftermarket filters are made to the Kubota specs for those with a built in magnet in the filter itself. Ya sure there are filters that will screw on and seal, but without the magnet they are NOT "oem equivalent" And if the filter maker could care less about the magnet, what other cost cutting moves are they going to make, IE less filtration media, paper end caps, etc. Stuff inside the filter you cannot see!
Yes, another company makes Kubota branded filters, but that in no way means that the same company that makes filters to "Kubota" specs is going to make another filter built to sell at a certain price point in a general discount store is going to build the "will fit" to the same specs as the oem Kubota.
So you save a few bucks on a filter, big deal, over the life of the machine if you save a few hundred in filters that are NOT the same as Kubota, what does that really mean when the cost to repair damage from some will fit filter can cost thousands. Penny wise and pound foolish comes to mind.
As to oil, there is a considerable amount of more information out there that allows you to compare the makeup of the oil to compare it with the oem Kubota specs. I would use a good quality motor oil meeting the specs, I prefer the SUDT though from Kubota for the tranny.
David