It sure isn't the only one that meets/exceeds Super UDT spec. Universal Torque Fluid, UTF Red. There are also other manufacturers that make suitable replacements.
I think SUDT is 5w30 equivalent and JT5 is 10w30 equivalent.
The specs on the bottle are recommended uses, not a guarantee that it meets the OEM specifications. Misleading, but it was written by the marketing departments...
Actually Kubota told me in a reply to a email question a while ago that it is 10W/20.
"Thank you for contacting Kubota Tractor. Our Super UDT fluid is unique to the industry. It is a special blend that is different that our standard UDT fluid, and most others in the market today.
The only information we are allowed to release is this.
The SAE viscosity Grade is 10W-20
ISO Grade is 46
Flash Point 183 "