When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
What you see is the wheel bearing adjusting nut. Remove it, and the hub will slide off. If you're doing this to replace the emergency brake shoes, it is not necessary---the shoes will come off with the hub in place.
What do I use to remove the filler bolt? Its an internal square design.
You just use a 3/8" drive ratchet to remove that plug. When I did my Nissan (which has the same type of plug) I found it easier to use a short extension though to put a little knuckle room between the drive ratchet and the diff, which might not be necessary on the Ford. Just be sure to use a little bit of thread sealant on the plug before you put it back in, just be careful not to get any in the case.