I got this info out of the Service manual.
Hydrostatic Transmission 0.60 US qts. (0.57 L) API service CD SAE 10w-30
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Transmission Case - T1400H 1.9 US qts. (1.8 L)
- T1400 2.7 US qts. (2.6 L)
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Multi-grade trasnmission fluid or gear oil SAE #90. The fluid listed below or equivelent are recommended.
Kubota - UDT Hydrostatic transmission fluid
Shell - Donax-TD Donax-TM
Mobil - Mobil Fluid 350, 423
Exxon - Torque Fluid 56
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I believe that you only need the top HST info but there you go. Hope that helps you out.