Since your engine is a non-sleeved motor, I would figure it would not need DCA2 or DCA4 additives. I know 7.3 Fords ain't sleeved and need it but this is a Kubota engine not IH.
Good antifreeze with distilled water mix 50/50 will work just fine.
The FleetGuard product dealer recommended was Universal LS PG Concentrate. Which is compatible with most green antifreezes. His emphasis was to use distilled water for the mix.