Changing Rear-end Fluid.

REad the @#$%$%^ owner's manual. It goes by mileage.

I've never seen a thread beaten to death before like this. The owner's manual tells you what you need to use and when. I don't think trying to second guess Ford when it comes to weights of fluids is a good idea.

BTW, what is the tightening bolt pattern for getting the rear cover back on?

Just go to this site...

http://e-toolbox.com/ads/index.cfm