a place to put rear end lube in and ck the level. I have a 02 F-150 5.4L w/ a 9.75" rear end. It's the FX4 model with the towing package. I looked for the fill plug that the book said it would be but it's not there. I looked all over the thing the best I could while under the truck not up in the air. ??????? where????????? is it???????

 

The plug is on the driver side of the driveshaft towards the front of the vehicle between where the driveshaft and the axle tube come into the diff. You will need a 3/8 ratchet to loosen it.