If you are adding to the dipstick to the front left of the gearshift you are adding oil in the right place on a Series IV as Allis combined the hydraulic and power director compartments on the D17 starting at Series III and eliminated the fill point up by the belt pulley location where your independent hydraulic pump is now located on a Series IV.
My question is where did you drain the oil from? Look at these 2 pictures. Did you drain the oil from here from these 2 power director drain plugs?
If you drained from a plug underneath the transmission/differential/rear axle that's another compartment that fills with the front RIGHT dipstick from the gearshift.
Note a Series IV takes 26 quarts to fill the PD/hydraulics. 24 quarts for the transmission/differential case. HTH. Mike