I have a noise (squealing or squeaking) coming from my 98 f-150 4x4. it is only in reverse and it is not constant. Its kind of like once every revolution of the drive shaft. No vibrations at any speed. Help!? The noise is driving me insane....my diff seems to be whining when i am driving on the highway, i thought it was just tire noise at first but seems to be getting louder.


......plus it is slowly leaking fluid at the pinion seal...i removed the diff fill plug and it had a good size chunk of metal stuck to it!!

what should be my next move??

 

Have you pulled the diff cover and check for play? If you replace the pinion seal, make sure to put in a new bearing too.

 

Is this a repost?

Either way, it's more that likely a u-joint. Bad u-joints are known to squeal in reverse, but not moving forward. Replace them and I bet your problem goes away.

As for the leaky pinion seal, it's a seperate issue. If the fluid level has gotten low enough, it's possible that the gears have overheated and become warped (or worse). If I were you, I would have a professional insepct the rearend.