Tom, my 3600 was hard to steer when I first started driving it. What I did, fill the steering box with gasoline, let it set for a couple days, then worked the steering wheel back forth and then pulled a lower bolt out, letting the old grease/gas drain. I actually did this little exercise a couple time. Then I filled it with
this. I did eventually rebuild the tierod ends, drag link and king pins. After all that it drives almost like it has power steering if you're moving at all. The steering sector flush and fill with 00 grease was an improvement, the rest was icing on the cake.
added in edit, be sure the tires have max air pressure recommended. Jack the front up and turn the wheels from lock to lock, checking for any binding, be sure to grease everything.
Good Luck
RR