Today i went in and got the rattle in the back taken care of. It turned out to be the hanger, was to long from the factory. And it was hitting the top of the muffler. So they replaced it. The tech said he had never seen this before. It was over a one inch longer than it should have been. They said they where sending back to Ford to find out what the problem is. So if you power brake over 2,500 rpms and hear a rattle in the back. Check out the hangers. On a side note i asked about getting 4.10 gears installed. The Service Mg said as long as they install it with Ford parts. It will not void my warranty. So i know what my next major mod well be.