The above posts are correct. You can use the shank in either the up or down position, it does not matter.
The torque specs are as posted above. I would torque to 275ft/lbs.
One additional comment:
Under the hitch head is a small square headed bolt that jams up against the shank. It keeps the hitch head tilt up against the washers behind the head. It should be tight before you tighten up those large shank bolts. It also has a tendency to loosen easily. Make sure you check the tightness of that bolt before every towing session or your hitch head may well bang up and down at every stop and start. The clamping force of those large bolts holding the head onto the shank are often not enough to hold the head tilt where it should be and up against the washers.
Barney