Gear Oil Leak!

[shooter]

I bought my 02 4.4i a month ago knowing that there was a valve cover gasket leak. When installing my x pipe yesterday, we looked under the car for the leak. It was barely a drip, no need of replacing yet.

The mess that I saw when I bought the car seems to actually be gear oil. It looks to be coming from this part right inside of the front right wheel. It's white and has a cylindrical shape. Can someone tell me what this is? I can take pictures if know one knows off the top of there head. It may be part of the differential we were thinking. One of my friends suggested the rear main seal, but the others thought otherwise.

Thx

[jst2878]

pics needed