You're correct...if the drag-link has correctly set length. If it is too short/long it will pull one side or the other. Think of it this way:
When You turn the steering wheel beyond dead ahead, You want servo assistance to turn the wheels.
If the draglink/steering box is incorrectly set up, i.e. the drop arm points this or that direction, it is efficiently the same as if You have already started turning the steering wheel, wanting servo assistance.
A first chk is then to measure the length of draglink (cfr manual for this).
To chk more thoroghly: If I remember correctly (chk manual) You can insert a pin to lock the steering box dead ahead. If the vehicle then turns one way or another, the drag link needs adjusting longer or shorter.
Then You will come in what's known as zero backlash position, and the vehicle stops pulling left or right.
But: First of all: Some claim gas charged steering dampers to pull on the steering, and as this is two nuts only, chk that first.
Happy spannering!