The early One-Seventy's with cream hood decals with the model spelled out were identical to the D17 Series IV's. They had the hydraulic pump on the right side of the torque tube in the front of brake pedals driven by a hollow quill shaft off the flywheel but separate from the foot clutch so you had independent hydraulics that worked with the foot clutch depressed.
Later black hood stripe 170's (model in numbers, not letters) had a redesigned front end with the hydraulic pump mounted in the front end casting and driven off the front of the crankshaft. There was a longer suction tube that ran back along the right engine side to the torque tube to access the hydraulic fluid reservoir.
In both versions, the torque tube casting was the fluid compartment for both the hand power director clutch and the hydraulics. It is filled with the dipstick to the left/front of the gearshift sitting in the seat. The transmission/differential housing was separate and filled via the right dipstick sitting it the seat.
It is not possible for transmission fluid to get into the engine oil crankcase on either version unless someone has seriously custom modified something. However it is very possible for the seals to fail on either the transmission input shaft or the rear PTO shaft and for it to pump fluid into the transmission/differential case and over fill it. This is a problem that does happen on these models. You have to split the tractor between the transmission/torque tube and replace the seals on both shafts to correct this.
Let me know if this helps at all. Mike