I've checked some of the alternative filter sources and the Kubota filter doesn't cross reference. I also talked to Kubota's regional office. They'd like a dealer to take a look at the filter assuming I get the filter to a dealer. The odd thing was that they have no previously reported instances of the filter failing in their warranty database contrary to some of the reports posted here.
Apparently the only way something gets in the database is if a dealer reports it. The hydraulic tube that Kubota replaced on the tractor under warranty because of an interference never made it into the database because the part came directly to me and I installed it.
They also have no record of a previous notice to dealers about a problem with the filter.