What kind of poor, thin metal is Ford using in their trucks? I found a puddle of grease under the truck, and after crawling under the truck guessed that I had a bad seal on the differential. I took it to a repair shop and they told me there was a hole in the rear differential cover. Of course the garage did not have the part needed which meant a couple of day's wait and another trip to the shop. I cannot fathom that Ford would use such poor, corrosion prone material for a differential... A PART THAT IS EXPOSED TO GEAR LUBRICANT and one would think was painted with something that would not allow rust. I am very disappointed in this and other corrosion related problems I have had with a vehicle with such low mileage..