I have heard two different stories to why the whining occurs from the rear end of some of these F 150's. Some say it is the casting of the rear end and that nothing short of replacing the whole thing will fix the whine. Others say that it is nothing but the ring and pinion that needs replacement. Well my question to all of you is which is it, I am taking my truck in this week to have the problem fixed for good and I need to tell them exactly what I want.

Please HELP!

 

Tell us more about your truck including model, engine, year, etc...

 

2004 SCrew XLT 5.4L with 8.8 axle w/ LS aprox 69,000 miles

 

how does the diff itself look? have you seen it? seen the spider gears? is there slop where the cross is? how are the clutch packs?

i just ran into something similar where it ended up being my diff itself

 

If you have a 5.4, you do not have a 8.8 rear. You have a 9.75. Only the front would be 8.8, assuming it is a 4x4.

 

Most of what I've heard points to the pinion bearings. Mine has whined for about 30K miles but runs just fine so who knows...I tried changing the Diff fluid w/ modifier but didnt help. 70K miles isnt much unless you offroad alot or tow frequently. I would still change the diff fluid just for good measure though