Ford Repair: Rear end, sound frequency, rear end

Question
Erik, I bought an 02 Explorer with 30k on it...I have a hum in the rear at 55-65mph and a little at 35...The dealer replaced my friends 05 axle under warranty, but on mine they are saying there is nothing wrong with it...That is impossible...I can hear the hum over my radio at at that speed. Do you have any suggestions or ideas of what this problem is...I know a LOT of people are complaining about it but nothing is being done??

Answer
Hello and thanks for the question...I'll try to help.
I would make sure that it isn't radial noise from the tires first. Have them rotated and see IF the noise changes location or sound/frequency. Then, if that doesn't solve the problem.......have the rear end checked.
Erik