I really can't figure this out and need help on this. I have dual gas tanks and what started happening is something I can't figure out. If I fill both tanks that truck will run fine, no problems. What is happening is when I am running on the rear tank it still runs but it is transferring the gas to the front tank?

I noticed this two days ago when I had approx. half a tank in each. I changed from the front to the rear and it was just eating up the gas, I couldn't believe it. I thought there was a problem so I switched it to the front tank and it was full!!

What in the world is going on, I have had this truck for 11 years and haven't had problems. Can someone enlighten me with some information so I can fix it?

Your truck has a check value to keep this from happening.
it is stuck letting the gas to go to front tank.

Your front FDM has failed with the shuttle valve stuck, causing fuel from the rear to return to the front tank. That's why it had more fuel in it than what you put. It's a known problem, and the only fix is a new FDM from Ford. Look through the rest of that album for info on dropping the tank to change it, but pickup owners often find it easier to remove the bed.