I buy Kubota parts from either Coleman Equip. CO., Online or Messicks online. You could also contact them For more specifics.
For engine oil, use the correct weight oil (most likely 10W 30 or 15W30) use Shell Rotella diesel engine oil, that's good stuff 👍
I'm not sure about the 3 hydraulic filters, although if it's Power steering,and a hydraulic dump bed I could see where it might have more than 1.
The best advice I can give you, search Ebay,Amazon where ever and find a Shop service manual, not a owners manual, but a Service manual.
They can run upwards of $60, but it is well worth it!