If it has 3 point hitch, it is a tel-e-flo. The early ones have the oil passages internal to the rear end and reservoir. They also have an all cast iron pump with only one hyd line connected to it for the power steering. The early system has only a small filter to the right of the lift cylinder.
The later system uses a pump that has aluminum front and back with an iron center plate. They also have a large ~1" inlet tube that goes from a canister type filter under the left side of the seat to the pump as well as a line that goes along the right side of the system to the front of the reservoir to supply oil under pressure to the unit. It will also have a smaller line that goes to the power steering.