The 3 point up or down doesn't make a big difference, just easier to check the level in a consistent way every time, so I do mine down ... My sight glass is on the back of the tractor, so less in my way ... Unless the backhoe is on!
A gallon of the Kubota SUDT fluid will be in the low $30's ... Add just a little at a time, and you will see it come up in the glass.