I don't think so. That's the VSS.
Look on the diff. for a SQUARE drive (3/8") plug, about 1/2 way up.
Pull the cover off to drain it. Clean it out.
Reinstall cover with a bead of RTV.
Fill it from the removed square drive hole till it runs out of that hole, with the truck level.
Reinstall square drive plug. Clean it all up for a leak check in a day or so.
I've heard SOME of the 8.8's needed a bit more lube, so Ford had them top it off a bit higher using the VSS hole. You'll be WAY too full if you fill it there, unless you are MEASURING (5 pints), then it'd be ok.