how to remove hydraulic oil

[rickv3]

I have a 1983 ford 1710 diesel compact tractor,4x4,have a service manual but does not state how to change hydraulic fluid,manual says the hydraulic oil is for transmission and drive train,and when you change the fluid to you replace fluid at the fill cap near the seat for the entire system,do you have to bleed anything,one more request have change voltage regulator Hitachi TLIZ-61D anyone no were to find or cross reference number

Thanks in advance