I should add that the MSDS do not tell the whole story. Maybe both SUDT2 and Premium UDT contain some magic additive proprietary to Kubota -- call it hexa-flufoline -- that is absolutely vital to the longevity of a Kubota transmission. I doubt it, but it's possible.
What the MSDS do tell us is that the two products are different in some ways. And that Kubota does not manufacture their branded fluids. It also implies that the regional arms of Kubota contract the manufacture of Kubota fluids independently, and that therefore, the "factory fill" may not be the same as the fluid available to the dealer and consumer in the region where the tractor is eventually sold.
Now, it would appear on the surface that the fluid sold in Canada is engineered for a colder climate than the fluid sold in the US. Would Kubota owners in Alaska, who might use their tractors primarily for blowing snow, be better off buying Premium UDT from Canada? Or would farmers in Southern Ontario, bringing in the hay during +30° August heat waves benefit from a source of US SUDT2? Or does it mean any quality, brand name hydrostatic transmission fluid like PetroCan's DuratranXL or John Deere Hyguard is good enough -- despite the lack of hexaflufoline?
I don't know. All I know is my archaic B7100, produced long before the magic fluids hit the market, has been happily putting away on Amsoil fluid for many years and the transmission hasn't seized up yet.