Big George,
Do yourself a favor and buy a couple of manuals for your tractor. See photo. They are chock full of pertinent info like this.
The drain for the rear axle is underneath just in front of the drawbar hanger. Sorry but I aint gonna crawl under there to snap a photo for you.
Fill with about 5 gallons till it runs out of the hole thw red pen is pointing to on the right side behind the foot rest.
DO NOT remove the slotted screw that is just below the check plug by the red pen or you will be sorry.