Well for the past month, everytime I backup (never when In Drive, just reverse) I've had a really LOUD and annoying SQUEEKING...Sounds like the bed is rocking back and forth and sounds like an old antique bed squeeking..Really bad...Well the other day I pressure washed under my truck (12-14 hours before) and drove about an hour away from work, came back...And it was gone...Not even quiter, but COMPLETELY gone.... Nothing...Now today it made a slow, but irritating comeback and its back in its original spot...Any ideas...

 

Probably had something stuck behind your drum brake, and every time you popped it in reverse it would dislodge itsel and start squeeking - maybe a piece of rock or something in there - the power washer probably blew it out =)

 

my buddy's ranger did that and it was a broken spring.. best way to know would be to take her apart and clean everything and see whats going on..