I have an 03' FX4 with the 4.6l. whenever I shift into reverse my truck starts squeaking...the faster I go in reverse the faster the squeaking gets...when I shift into neutral and roll backwards the squeaking stops. I dont understand why it is doing this. any help would be appreciated!

 

Have you checked the Ujoints?

 

yea, they seemed to be fine.

 

That a sign of your u joints replace them