I have a Ford F 150 that has graphite for lub in the rear end.

HIGHLY recommend referring to the owners manual for lubrication specifications!!

I have never heard of graphite being used as a rear differential lubricant. They use 90 wt oil or synthetic.

I assume you are referring to changing an axle shaft bearing? The rear differential requires 75W-140 Synthetic Rear Axle Lubricant. If it has the **Traction-Lok axles**,then you'll need to add (4 oz.) of Additive Friction Modifier also,if not, don't add the Friction Modifier. I've never heard of "Graphite" in the rear differential unless you meant the Friction Modifier ADDITIVE! I have the same truck you have and have my owners manual right-cheer! If you don't have an owners manual,see pushrods answer on that FREE download,owners manual is a must for me.